820-3476 A1502 Quarter Fan Spin Loop

[Don Anton]

Hi All,
Tis board came as liquid damaged but not much. bit near clock chip/tiny bit on R5351 near SMC and R1410 PM_BATLOW_L TP was gone but resister by itesl and the pads are fine.
Anyway I replaced the CLockchip and Y1905, R1410, U1950 but no change.
PM_BATLOW_L is 3.3v and all the power rails are present including CPU_Vcore on the movement of fan spins. I reflow the SMC still same.
I change the bios with same board then fan goes continuously but no chime no Display. also there is no USB mouse continue light .

Any advice will greatly appriciate.

 

[2informaticos]

So board stays on, with all voltages after BIOS chip replaced?
That confirm BIOS corruption at least.
I recommend to test with known good BIOS file; clean ME, of course.

 

[Don Anton]

Hi, thank yu for your reply. Sorry some how now for any bios it is same behavior. I tried with clean me and thr same bios I tried before but quarter fan spin loop
Could this be SMC?

 

[2informaticos]

Replace SMC and see if symptom changes.

 

[Don Anton]

Will do and update . thank you very much.

 

[Don Anton]

Hi Replaced SMC still same issue.

 

[2informaticos]

Put back its BIOS chip.
If still stays on, but no activity, means heat affected board; wasn't BIOS issue.
Try to start in SMC bypass too.