w9gb wrote:
On my unit, found one of the transformer's secondary wires from transformer
not fully seated on the PC board -- that was it -- working like a champ.

It is likely many UPS have been dumped for just that.

When these APC units fail --- the top 3 reasons / problems:

1. Bad lead-acid batteries
2. Charger circuit bad (can not properly charge battery)
3. Internet circuit (can not produce 120 VAC from good battery).

Inverter circuit?