故障现象：
1. 开机有声音
2. 背面logo亮灯
3. 键盘背光灯不亮
4. 大写锁定键按下不亮
5. 屏幕黑屏，无苹果logo
解决：重置pram后成功开机。
附1：apple技术顾问的软件重置操作
重置 pram (parameter ram)
1. 关闭 mac。
2. 在键盘上找到以下按键：command (⌘)、option、p 和 r。您需要在步骤 4 中同时按住这些键。
3. 启动电脑。
4. 出现灰屏前按住 command-option-p-r 键。
5. 按下这些键，直到电脑重新启动，您会再次听到启动声。
6. 松开这些键。
重置 smc/重置系统管理控制器
1. 关闭电脑。
2. 将 magsafe 电源适配器连接到电源和 mac（如果尚未连接的话）。
3. 在内建键盘上，同时按下（左侧）shift-control-option 键和电源按钮。
4. 同时松开所有键和电源按钮。
5. 按下电源按钮打开电脑。注：重置 smc 时，magsafe 电源适配器上的 led 指示灯可能会更改状态或暂时关闭。
附2：开机后系统日志
…
15/1/16 上午10:39:10.000 kernel[0]: bug in process suhelperd[255]: over-released legacy external boost assertions (1 total, 1 external, 0 legacy-external)
…
15/1/16 上午10:39:19.366 coreservicesuiagent[226]: unexpected message <os_xpc_error: <error: 0x7fff726e1c60> { count = 1, contents =
“xpcerrordescription” => <string: 0x7fff726e1f70> { length = 18, contents = “connection invalid” }
}>
15/1/16 上午10:39:19.370 coreservicesuiagent[226]: unexpected message <os_xpc_error: <error: 0x7fff726e1c60> { count = 1, contents =
“xpcerrordescription” => <string: 0x7fff726e1f70> { length = 18, contents = “connection invalid” }
}>
15/1/16 上午10:39:19.877 com.apple.xpc.launchd[1]: (com.apple.imfoundation.imremoteurlconnectionagent) the _dirtyjetsammemorylimit key is not available on this platform.
15/1/16 上午10:39:20.113 icbaccountsd[306]: connection error while checking apple internalness. error: error domain=nscocoaerrordomain code=4099 “未能与帮助应用程序通信。” (the connection to service named com.apple.crashreportersupporthelper was invalidated.) userinfo=0x7fe780500860 {nsdebugdescription=the connection to service named com.apple.crashreportersupporthelper was invalidated.}
…
15/1/16 上午10:39:20.000 kernel[0]: bug in process suhelperd[255]: over-released legacy external boost assertions (0 total, 0 external, 0 legacy-external)
…
15/1/16 上午10:39:28.233 reportcrash[320]: saved crash report for alipaydispatcherservice[26] version ??? to /library/logs/diagnosticreports/alipaydispatcherservice_2015-01-16-103928_soybean-macbookpro.crash
…
15/1/16 上午10:39:32.000 kernel[0]: utun_ctl_connect: creating interface utun0
15/1/16 上午10:39:32.000 kernel[0]: utun_start: ifnet_disable_output returned error 12
15/1/16 上午10:39:33.789 racoon[326]: failed to bind to address fd02:f9e5:3d9b:c8b:f9e2:928f:e6c7:f5f5[500] (can’t assign requested address).
15/1/16 上午10:39:33.790 racoon[326]: failed to bind to address fd02:f9e5:3d9b:c8b:f9e2:928f:e6c7:f5f5[500]: because interface address is/was not ready (flags 2).
15/1/16 上午10:39:33.790 racoon[326]: failed to bind to address fd02:f9e5:3d9b:c8b:f9e2:928f:e6c7:f5f5[4500] (can’t assign requested address).
15/1/16 上午10:39:33.790 racoon[326]: failed to bind to address fd02:f9e5:3d9b:c8b:f9e2:928f:e6c7:f5f5[4500]: because interface address is/was not ready (flags 2).
…
15/1/16 上午10:40:04.925 loginwindow[66]: error | -[sessionlogoutmanager quitfinder] | finder is killable, calling smjobremove
15/1/16 上午10:40:04.927 windowserver[95]: cgxgetconnectionproperty: invalid connection 32527
15/1/16 上午10:40:04.927 windowserver[95]: cgxgetconnectionproperty: invalid connection 32527
15/1/16 上午10:40:04.927 windowserver[95]: cgxgetconnectionproperty: invalid connection 32527
15/1/16 上午10:40:04.927 windowserver[95]: cgxgetconnectionproperty: invalid connection 32527
15/1/16 上午10:40:04.927 windowserver[95]: cgxgetconnectionproperty: invalid connection 32527
15/1/16 上午10:40:04.927 windowserver[95]: cgxgetconnectionproperty: invalid connection 32527
15/1/16 上午10:40:04.931 loginwindow[66]: login window point of no return
15/1/16 上午10:40:04.937 com.apple.xpc.launchd[1]: (com.apple.coreservices.uiagent[226]) service exited due to signal: killed: 9
15/1/16 上午10:40:04.973 sharingd[196]: 10:40:04.973 : sigterm received, shutting down.
15/1/16 上午10:40:04.941 com.apple.xpc.launchd[1]: (com.apple.lateragent[314]) service exited due to signal: killed: 9
15/1/16 上午10:40:04.979 lsuseractivityd[214]: [sfactivityadvertiser] error: lost xpc connection
15/1/16 上午10:40:04.952 com.apple.xpc.launchd[1]: (com.apple.internetaccounts[224]) service exited due to signal: killed: 9
15/1/16 上午10:40:04.982 lsuseractivityd[214]: [sfcontinuityscanmanager] error: lost xpc connection
…
15/1/16 上午10:40:05.000 kernel[0]: kext loading now disabled.
15/1/16 上午10:40:05.000 kernel[0]: kext unloading now disabled.
15/1/16 上午10:40:05.000 kernel[0]: kext autounloading now disabled.
15/1/16 上午10:40:05.000 kernel[0]: kernel requests now disabled.
15/1/16 上午10:40:05.000 kernel[0]: applecaminuserclient::clientdied
…
15/1/16 上午10:40:40.000 kernel[0]: appleintellpssi2c::probe fails
15/1/16 上午10:40:40.000 kernel[0]: appleintellpssdmac::probe fails
15/1/16 上午10:40:40.000 kernel[0]: appleintellpssi2c::probe fails
15/1/16 上午10:40:40.000 kernel[0]: appleintellpssi2c::probe fails
15/1/16 上午10:40:40.000 kernel[0]: appleintellpssgspi::probe fails
15/1/16 上午10:40:40.000 kernel[0]: appleintellpssdmac::probe fails
15/1/16 上午10:40:40.000 kernel[0]: appleintellpssi2c::probe fails
…
15/1/16 上午10:40:40.940 watchdogd[31]: [watchdog_daemon] @( wd_watchdog_open) – ioiteratornext failed (kr=0)
15/1/16 上午10:40:40.941 watchdogd[31]: [watchdog_daemon] @( wd_daemon_init) – could not initialize the hardware watchdog
15/1/16 上午10:40:40.941 watchdogd[31]: [watchdog_daemon] @( main) – cannot initialize the watchdog service
…
15/1/16 上午10:40:41.000 kernel[0]: previous shutdown cause: 5
…
15/1/16 上午10:40:41.442 secinitd[96]: ctkd[95]: unable to get root path for bundle of main executable: /system/library/frameworks/cryptotokenkit.framework/ctkd
…
15/1/16 上午10:40:41.532 kdc[61]: warning found kdc certificate (o=system identity,cn=com.apple.kerberos.kdc)is missing the pk-init kdc eku, this is bad for interoperability.
…
15/1/16 上午10:40:41.928 apsd[50]: unable to bootstrap_look_up connection port ‘com.apple.askpermission.aps’ for user 0: unknown service name
…
15/1/16 上午10:40:45.908 imdpersistenceagent[228]: sacshieldwindowshowing:925: error: null response
…
15/1/16 上午10:40:51.000 kernel[0]: bug in process suhelperd[283]: over-released legacy external boost assertions (1 total, 1 external, 0 legacy-external)
15/1/16 上午10:40:51.000 kernel[0]: bug in process suhelperd[283]: over-released legacy external boost assertions (1 total, 1 external, 0 legacy-external)
15/1/16 上午10:40:51.000 kernel[0]: bug in process suhelperd[283]: over-released legacy external boost assertions (1 total, 1 external, 0 legacy-external)
15/1/16 上午10:40:51.000 kernel[0]: bug in process suhelperd[283]: over-released legacy external boost assertions (1 total, 1 external, 0 legacy-external)
15/1/16 上午10:40:51.000 kernel[0]: bug in process suhelperd[283]: over-released legacy external boost assertions (1 total, 1 external, 0 legacy-external)
15/1/16 上午10:40:51.000 kernel[0]: bug in process suhelperd[283]: over-released legacy external boost assertions (1 total, 1 external, 0 legacy-external)
15/1/16 上午10:40:51.000 kernel[0]: bug in process suhelperd[283]: over-released legacy external boost assertions (1 total, 1 external, 0 legacy-external)
…
15/1/16 上午10:40:56.894 racoon[297]: failed to bind to address fd02:f9e5:3d9b:c8b:81c:9997:4533:a06a[500] (can’t assign requested address).
15/1/16 上午10:40:56.894 racoon[297]: failed to bind to address fd02:f9e5:3d9b:c8b:81c:9997:4533:a06a[500]: because interface address is/was not ready (flags 2).
15/1/16 上午10:40:56.894 racoon[297]: failed to bind to address fd02:f9e5:3d9b:c8b:81c:9997:4533:a06a[4500] (can’t assign requested address).
15/1/16 上午10:40:56.894 racoon[297]: failed to bind to address fd02:f9e5:3d9b:c8b:81c:9997:4533:a06a[4500]: because interface address is/was not ready (flags 2).
…
15/1/16 上午10:40:58.672 coreservicesuiagent[231]: unexpected message <os_xpc_error: <error: 0x7fff7bc50c60> { count = 1, contents =
“xpcerrordescription” => <string: 0x7fff7bc50f70> { length = 18, contents = “connection invalid” }
}>
15/1/16 上午10:40:58.676 coreservicesuiagent[231]: unexpected message <os_xpc_error: <error: 0x7fff7bc50c60> { count = 1, contents =
“xpcerrordescription” => <string: 0x7fff7bc50f70> { length = 18, contents = “connection invalid” }
}>
…
15/1/16 上午10:48:33.359 coreservicesuiagent[231]: error -60005 creating authorization
