820-2850 green light, fan spin, no chime or video

With board in case and fully connected I get green light, fan spin, no chime or video

With board removed, battery disconnected and charger attached I get no fan spin.
ppbus_g3h and pp3v42 good.
S0 and S3 rails 0 volts.
pm_slp_s4_l = 0v
pm_batlow_l = 0v. (wont this always be low with no battery connected anyway causing the low pm_slp_s4_l ??????)

Only when I connect the battery, then connect the charger I get fanspin. No USB activity

Whats going on?

Do you have 85W charger for sure?
This board doesn't start with 45-60W charger alone, unless battery is connected.

I was using a 60W charger! I didn't know about the 85W requirement
I switched to using an 85W charger and I am getting the same symptoms but now not needing the battery connected to get some activity.

So still no chime or video or USB activity.

Wondering where to go from here

What is the CPU core voltage?

ppvcore_s0_cpu is 0.82v
ppvcore_s0_gfx is 0.88v
gpu_vcore_vid0 is 3.3v
fans at full speed, no usb activity

Did you change C9560?
BTW, don't use hot air!

C9560 changed just now but still no USB activity visible on snow edition memory stick.
PP1V8R1V55_S0GPU_ISNS_R only achieving 1.56v
No video

"1V8R1V55"
Why not good 1.56V?
If was 1.8V you've complained why not 1.55V then?

Any history fault available?
Try known good BIOS.

Oh does that "1V8R1V55" mean 1.8v or 1.55v is ok?
History: owner said it was bought refurbished from Apple. Had a loose hinge screw that just needed tightening. No corrosion evident.
Im a BIOS virgin Im afraid. I do have a CH341A programmer bought in anticipation. Hope it will do. I don't have a known good BIOS file as just starting out. Would you be able to supply?

I think was already posted on the forum...

I used my CH341a programmer to write each of the two provided binaries to the Flash chip.

APPLE A1286 MLB 820-2850-A OK resulted in no fan spin.
PCT25VF032B_20160916_185643 still got fanspin but still no chime.

Should I be expecting a chime to occur when board is devoid of all peripherals (except speaker)

Would a working board chime if not connected to keyboard, trackpad etc?

Chime is not the best "life sign".
Check for USB activity instead; on both ports.

There is an initial blink on the 2 snow edition drives in the USB ports at start of fanspin but no further flashing
Fans do ramp up to full after a short while.

Board gets stuck, very likely because of bad GPU.
You can try to disable it; lot of work to do...

I think customer would welcome disabled gpu if there are onboard graphics available. Would you have a pointer to disabling GPU?

A lot of work to disable GPU on this board.
All the info already posted on the forum...