BNT-500AP does not see the battery?

Question

Uninterruptable power source

There is a PowerCom BNT-500AP UPS with RS-232. I took out the battery, it is 1.5 volts, well, it is completely discharged. Right now I connected the UPS without a battery, it does not emit any signals. I monitor using the UPSMON PRO program, it writes that the battery is 100% charged (I connect it to a PC using a Chinese adapter with a CH340 chip). Of course, I know that it’s worth changing the battery right away and the Chinese adapter doesn’t give it away, but maybe he doesn’t see it at all? How can anyone fix this? Also, what com port settings do you need to set?

Answer 1

Testing is in progress, but in the end the battery is written OK, but it is not there)

Answer 2

It is necessary to connect a working one, such a reaction to the charging voltage is possible.
The UPS sees the voltage it produces to charge the battery and thinks it has a fully charged battery.