apc back-ups 1100va

Hello! I recently (2-3 month ago) purchased an APC Back-UPS Pro Gaming (BGM-series) and have noticed a very high-pitched squealing or buzzing sound coming from inside the unit every few minutes. It’s not the normal beeps or alerts - it sounds like coil whine (vibration from inductors or...

I currently have an APC Back-UPS 1100VA (specifically, BX1100L-MS) and I was wondering if it's safe to place it in the desk? Specifically near the monitor or PC? Or should I just put it under the desk? Additionally, how can I check compatible batteries for my UPS? I'm planning to buy a CSB...