RH2288 V3上电失败，且多次更换备件未解决

硬件配置：RH2288 V3+CPU（1ps）+内存（1ps）+其它

问题现象：BMC上电失败

分析BMC日志：

1、sel日志：上报"PwrOk Sig. Drop"（异常掉电）和"PwrOn TimeOut"（上电超时）

1828,"Normal","2019-07-04 Thursday 03:31:42 ","ACPI State","Power off state",2206FFFF,"Asserted"

1829,"Major","2019-07-04 Thursday 03:31:42 ","PwrOk Sig. Drop","Power supply failure",0801FFFF,"Asserted"

1830,"Normal","2019-07-04 Thursday 03:31:43 ","DIMM000","Presence detected, dimm is 0/0/0",0C86FFFF,"Deasserted"

1831,"Major","2019-07-04 Thursday 03:31:53 ","DISK1","Hard disk drive fault",0D81FFFF,"Deasserted"

1832,"Normal","2019-07-04 Thursday 08:26:26 ","Port2 Link Down","Slot is Disabled",2188FFFF,"Deasserted"

1833,"Normal","2019-07-04 Thursday 09:29:53 ","UID Button","Uid button pressed",0341FFFF,"Asserted"

1834,"Normal","2019-07-04 Thursday 09:29:54 ","UID Button","Uid button pressed",0341FFFF,"Asserted"

1835,"Normal","2019-07-04 Thursday 09:29:54 ","Power Button","Power button pressed",1400FFFF,"Asserted"

1836,"Major","2019-07-04 Thursday 09:29:55 ","PwrOn TimeOut","Power supply failure",0801FFFF,"Asserted"

1837,"Normal","2019-07-04 Thursday 09:30:03 ","Power Button","Power button pressed",1400FFFF,"Asserted"

1838,"Normal","2019-07-04 Thursday 09:30:06 ","UID Button","Uid button pressed",0341FFFF,"Asserted"

1839,"Normal","2019-07-04 Thursday 09:30:17 ","UID Button","Uid button pressed",0341FFFF,"Asserted"

1840,"Normal","2019-07-04 Thursday 09:30:38 ","Power Button","Power button pressed",1400FFFF,"Asserted"

2、maintaince_log：上报pg_vddq_ab_fail_n asserted和pg_vcc_2v5_cd_fail_n asserted

2019-07-04 03:31:43 ERROR: pg_vddq_ab_fail_n asserted(1->0)

2019-07-04 03:31:43 ERROR: pg_vddq_cd_fail_n asserted(1->0)

2019-07-04 03:31:43 ERROR: pg_stby_1v05_pch asserted(1->0)

2019-07-04 03:31:46 ERROR: pg_stby_1v05_pch deasserted(0->1)

2019-07-04 09:47:25 ERROR: pg_vcc_2v5_cd_fail_n asserted(1->0)

2019-07-04 09:47:37 ERROR: pg_stby_1v05_pch asserted(1->0)

2019-07-04 09:47:40 ERROR: pg_stby_1v05_pch deasserted(0->1)

2019-07-04 09:48:01 ERROR: pg_stby_1v05_pch asserted(1->0)

2019-07-04 09:48:04 ERROR: pg_stby_1v05_pch deasserted(0->1)

2019-07-04 10:08:14 ERROR: pg_stby_1v05_pch asserted(1->0)

2019-07-04 10:08:17 ERROR: pg_stby_1v05_pch deasserted(0->1)

3、根据已有案例：

4、当前内存仅有1ps（DIMM000）,属于DIMM_ab区间，而DIMM_cd区间并无内存

5、根据日志报错内容，分别派件CPU、内存、主板，最终问题并未解决

重新确认现场操作步骤，发现现场在更换备件以及验证操作时，并未按照“最小化”规则排查。

指导现场最小化操作，仅保留主板+cpu+内存+psu模块，发现能正常上电，而在加上硬盘背板之后，异常复现，最终确认为硬盘背板故障。

硬盘背板导致上电异常,更换硬盘背板