Customer has a Vodavi XTSc-IP KSU with the V86 MBU. Extension 100 show NO SYNC. The KSU has several boards added. None of the LEDs on the various add on boards light up.

There are 3 LEDs located by the PMU board (a daughter-board the mounts to the MBU). They are also close to the battery.
1. When I power up on the mains (AC) the bottom LED (LD1) comes on faintly and LD2 and LD3 are both not illuminated.
2. When I jumper 24 V DC into the backup power supply input the bottom one (LD1) burns brightly, LD2 burns faintly, and LD3 doesn't illuminate.

I am thinking bad power supply capacitors but am looking for advice. The non-volatile memory battery (1/2 AA lithium) is dead, which I will replace.

Any ideas if which capacitors would be the culprit? Or any other test I should run?