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Once booted works fine on battery including sleeping but if I shutdown and dont have charger connected it wont boot. Where should I start?

Those 3 links Level 1,2,3 just lead to download of same file MBP-Anti-CrashLevel1.dmg Anyway, I elected just to replace all 3 FDMF6808N with FDM6708 but the problem has not changed - repeating partial boot

Tried safe mode, fans full blast, boot still died with loss of screen as before. How do I find this software mod you are talking about? I trust its a way to turn disable graphics chip. And how would I apply it when it wont boot? Ive never found ASD for this model A1398 2015 15,1. Does it exist...

Replaced 95828, board now boots :)

I took a look at those and none cracked or cratered. This is embarrassing. This laptop was working fine - just came in for new speakers (logic board had to come out) and had a bloated battery so I replaced that too. Customer admitted speakers never good after liquid ingress some time ago but...

Sadly this A1398 came in came in for speakers+battery and now after the required logic board removal it doesn't boot fully. Evidence of historic liquid entry near fan but no corrosion visible after extensive search. Removed battery, IO board, keyboard, trackpad and screen, connected HDMI...

I have to say my 'known good BIOS' should really only be 'assumed good' as it was from another yet to be repaired 820-00840. Worth trying a reprogrammed BIOS. Late here in Oz - something for tomorrow. Thanks

Just tried known good BIOS - no difference still 0v on L7210/20 How could a cpu problem explain why 0v at L7210/20 ? Surely lack of voltage here means no power to cpu.

0v at L7210/20 4.5ohm to gnd at each one pp5v_s0 5v ppbus_g3h_cpu 13.06v

This board had corrosion on components C7101, R7101, R7132 and tracks connecting to U7100 After replacement of above and U7100 I have 0.95v on L7410/20/30 all_sys_pwrgd 3.2v pm_sysrst_l 3.3v put_rst_l 3.3v Fan spins initially then stops then spins long time. Currents remains at 0.45a with SSD...

New U9580 and correct PSU and board now boots. Thanks for your help

A new U9580 now gives me a constant 2.5v on PP2V5_NAND_SSD0 :) and I see currents ranging up to around 0.3amps before it finally reduces to 0.00 amps so I suspect its getting further along. When connected only to screen no change in behaviour. When I get into DFU mode, cut jumper lead and try...

Can you suggest a next step? Ive got a new U9580 (TPS62180 on order) as it is not outputting yet it has input powered 12.6v and enable 1.8v

Revive appears to timeout with "System cannot be restored on this device - Gave up waiting for device to transition from DFU state to DFU state". Even "Restart Device" which I consider a safe option fails with message "Configurator could not perform the requested action - Apple Controller...

I wondered. Is the idea to restore? Does this wipe customers files - as the screen message alludes to?

pp1v2_awake 1.2v pp1v8_awake 1.8v pp3v3_awake 3.3v ppvddcpu_awake 0.75v pp0v8_slps2r 0.8v pp1v1_slps2r 1.1v pp1v8_slps2r 1.8v Tried to get DFU mode via instructions on https://logi.wiki/index.php/DFU_Mode_Restore_(Macs) AND via momentary short of SWK003 to no effect on A1502/BigSur/AC2. Then...

Diode mode on pp2v5_nand_ssd0 is 0.35v

20v 30mA on all USBC Dead machine, corrosion on C9583, C9584, both replaced but pp2v5_nand_ssd0 still 0v U9580 reflowed then lifted and refitted - no change. Board otherwise immaculate. ppbus_g3h 12.6v pp3v3_g3h 3.3v pp5v_g3h 5.1v pp1v8_slps2r 1.8v pp1v8_slp2rsw_dfr 0v pp1v8_awake 1.8v...

Hi, all solved after doing a better job of soldering on the U7100. Thanks for your help.

Ooops spoke too soon. During every boot as it is increasing current gain it shuts off every time just as it goes through 2 amps draw. Still shuts off booting with battery disconnected. Still shuts off in SMC bypass mode.