820-02100 20v 70mA apple logo appears for 4seconds, dies.

[Outofwhack]

Pressing power button when on charger [or on battery] would result in Apple logo for 2 seconds before shutoff.
Original battery was not charging. Battery replaced, battery now charges. Given a good charge.
Still only reaches Apple logo before shutoff.
Corrosion on CF800, CF813 but DM voltages good.
Corrosion on CN484, UF700 cleaned up
Corrosion around UR660, UR630 cleaned up

CD3217 restarts every 17 seconds. All I think
ppbus_aon 12.3v
pp3v8_aon 3.8v
pp5v2_s2 5.2v
pp1v2_awake 1.2v
pp1v2_s2 1.2v
pp3v3_s2 3.3v
pp3v3_aon 3.3v
pp1v8_aon 1.8v
pp1v8_awake 0v 3kohm to gnd

 

[2informaticos]

"CD3217 restarts every 17 seconds"
Possibly dead NAND there...

 

[Outofwhack]

The voltage levels for the NANDS appear good. Doesn't a bad NAND normally develop a short that would pull these down?
pp0v9_nand0 0.9v
pp1v2_nand0 1.2v
pp2v5_nand0 2.5v

ppvin_p3v8nand0 3.8v
I noticed ppvdd_ldo_nand0_ocarina is only 1.4v rather than schematics 2.5v
Before the CD3217 negotiate 20v ppbus_aon is 12.3v
After the CD3217 negotiates 20v ppbus_aon is 12.0v

Both DFU revive and restore fail with error 21.

Does appearance of the Apple logo mean its got to the point where its trying to read the NANDS?