I use one of these regularly. I've never had an issue with the battery door, however . . . . for a while, i kept getting dropouts. In order to overcome this i did the following:
1. I stopped leaving the receiver on top of my amp and placed it on the floor. Apparently, they don't like metal underneath them as it affects reception
2. When setting it up, i choose the channel that has the least interference, indicated by the reception lights on the receiver.
3. The transmitter has two modes - RF-1 and RF-2. The newer ones ship with RF-2 programmed, This is designed to minimise interference with wifi devices. I've changed mine back to RF-1. Do an online search to find out how as i can't remember and it's not obvious.
It now works faultlessly. I use rechargeable batteries in it and charge before each gig.