Battery connectors inside a UPS, F1 for F2 subsituted, consequences?
Those batteries are not really suitable

The datasheet for the batteries does not give a maximum discarge rate or current draw, but does indicate that the capacity is cut in half at 8 amps. At 12A, the voltage drops to 10V after only 8 minutes.

At full load, a 2.2kVA UPS will draw 45A from a 48V battery bank. Since you have two parallel sets of four batteries in series, that is 23A per battery. Drawing that much current will cause the battery voltage to drop a lot. The UPS then detects the voltage drop, and decides the batteries must have failed.

All is not lost though - if you keep the current draw low, then the voltage will probably stay up, and the UPS is more likely to work. What load you can manage will depend on details of the UPS which we don't have, so you'll just have to go by trial and error.