I decided to open thread here for information sharing purposes, if anyone owns same UPS as I have (5PX2200iRT). I got problems after one year of use. The IPP sofware (UPS management) shows that battery has not received any charging, ie status is at fully empty battery. When primany network failed, UPS did not anymore protect from power failures. On front panel it did show errors, with a comment "service needed". In UPS menus, following error seen --> "Battery fault, code 0x607".
UPS battery voltage is nominally 4*12V. I measured voltage (at old UPS battery), it was 52.58V. That means a normal voltage level, and most propably charging circuit in UPS did not correctly regognize the battery. I was informed by tech support, that the UPS will normally shutdown itself if the SLA battery cell voltage goes below 1.6...1.65V level (6 cells per 12V battery).
old UPS (manufactured at spring 2015)
catalog nb: 5PX2200iRTN
P/N: 9210-7374-KIT
Rev: 01
new UPS (date not known)
catalog nb: 5PX2200iRT
P/N: 9210-7374-00P
Rev: 01
Repair solution was to get a new unit, since current UPS was under warranty. New UPS has been tested, and the final installation is still to be done. I will later post here update, how the UPS works after longer time.