Battery Not Charging

I called WFCO tech line. Guy said to disconnect the battery then turn on all/most dc loads in camper, while also connected to shore power, then check for dc output from convertor to the battery both at the convertor, with panel cover removed and at the battery itself. Also possible is a dead cell in my battery which I doubt as my charger is designed to detect such issues. The convertor runs in parallel with the battery and puts out enough dc volts to charge the battery while in camper's in use.
Fingers are crossed to avoid buying a new convertor. The warranties are only to the original owner.
I just checked the battery with a load tester and it seems OK but still could have a cell that vibrates apart? The pods convertor does what it's supposed to do at the panel and at the battery connection.
battery is an Exide deep cell one year old.
It's possible that my battery was so discharged that it "made me think" I had another issue or- the dead cell thing...?

Is that a direct fit replacement, or is some surgery needed?

Can anyone tell me what voltage the converter is supposed to charge to?  On shore power overnight I am getting a battery voltage reading of about 12.5. The battery is less than a year old.

The converter should put out 13.2-14.4 volts. You don't say but I'm assuming the 12.5V is measured at the battery with the converter plugged in. If true my guess is the reverse polarity fuses in the converter are blown. The converter has two high current fuses to protect the converter from a reversed battery. They will blow if the battery is ever connect backwards even for an instant. You can test the fuses with an ohmmeter or by disconnecting the battery and plugging in the converter. With the battery disconnected a working converter should power the lights and fan. If not, and all the circuit breakers are on, it's probably the reverse polarity fuses. A fully charged battery should read 12.6+ volts with no load.