Continuous beep and won't start

[Anonymous user]

Hello,

I have an old APC BACK-UPS PRO 420SI. Some moths ago I tried it, and it works. Yesterday I tried it again, but without success. I plug the power cord into it and its only beeping countinuously and I can't swith it on. None of the leds are lighting or flashing.
I waited approx 20 minutes before I disassembe the UPS and and disconnect the battery power from the panel (because the beeping was horrible).
What can I do to make these old UPS to work?

Best regards,
Sipi-

(sorry my poor english)

[BillP · Accepted solution]

Hello,

It could be that the battery has gone bad. Do you happen to have a voltmeter and be able to measure the battery voltage?