KX55 5S22主板不开机（ 5800-A8S820-0P30)， 测主板F0A5处对地短路，查DC/DC供电,当脱开
U0P2(MSH6110AI)不短路，测L0P6电感处对地为120欧偏小，说明主芯片U1(MSD6A638JSM-003D)短路，
换U0P2和U1再升级主程序开机都正常。
5S22故障为不开机，通电连接串口打印信息如下
clkgen reg:
00h:| 0000h 0000h 0000h 0100h 0000h 0000h 0000h 0000h
08h:| 0000h 0000h 0000h 0000h 0000h 0000h 0000h 0000h
10h:| 0001h 0000h 0000h 0C00h 0C0Ch 0000h 0044h 0124h
18h:| 0900h 0C0Ch 0001h 0000h 0000h 0808h 0002h 0000h
20h:| 0100h 011Ch 0101h 0101h 0101h 000Dh 0101h 1D01h
28h:| 1D1Dh 011Dh 001Ch 0111h 0000h 0000h 0000h 0000h
30h:| 0101h 010Dh 0011h 0101h 0101h 0101h 0000h 0000h
38h:| 0000h 0101h 0100h 0101h 0101h 0000h 0001h 1111h
40h:| 0000h 0100h 0001h 0000h 1100h 0000h 0000h 0000h
48h:| 0000h 0000h 0000h 0000h 0101h 0101h 0101h 0011h
50h:| 0000h 1100h 1C00h 0000h 2120h 1121h 0101h 0101h
58h:| 0001h 0121h 0000h 0000h 0000h 0100h 0000h 0101h
60h:| 0000h 0000h 0000h 0101h 006Ch 0000h 0000h 0000h
68h:| 0000h 0001h 0000h 0000h 0101h 0000h 0000h 0000h
70h:| 0000h 0000h 0000h 0000h 0000h 0000h 0000h 0000h
78h:| 0000h 0000h 0000h 0000h 0000h 1D00h 0001h 0000h
[ eMMC_FCIE_DumpDebugBus() ]
0x15 = 2h, 0x38 = 0h, 0x39 = 3500h
0x15 = 4h, 0x38 = 0h, 0x39 = 3500h
0x15 = 6h, 0x38 = 0h, 0x39 = 3500h
0x15 = 8h, 0x38 = 0h, 0x39 = 3500h
CMD state: 000000h
FIFO status: 000000h
ADMA Address: 000000h
ADMA blk cnt: 000000h
[ eMMC_CheckR1Error() ] eMMC Err: eMMC_ST_ERR_R1_23_16
0x2C7DA0D4: 0Dh 00h 40h 09h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h 00h | ..@………….
[ eMMC_CMD13() ] eMMC: CMD13 check R1 error: 80000A05h, should not retry
[ eMMC_Dump_eMMCStatus() ] eMMC St: 0h 40h 9h 0h
eMMC die eMMC_FCIE_ErrHandler_Stop() Ln: 260
更换EMMC 烧写引导，升级主程序即可。