Late last year my PLB failed to light on test. The three flashing lights failed to flash.
Following conventional wisdom I brought a new one, a bargain at $356.
A couple of months ago, I thought I had better dispose of the old one responsibly and set about removing the batteries for proper disposal.
I was surprised that there were no anti tamper screws or glued components, three coarse plastic screws and that was it. Two 6 volt batteries piggy backed on the circuit board and the whole lot just slid out, further to my surprise the batteries had a replacement date, a quick look on line, $25.75 each. Bugger!!
I noticed the battery plugs looked just like the plugs on the batteries in my R/C boat.
Beauty!
A look on line about charging lithium manganese batteries revealed nothing sinister, on the charger they went. I tested the charger and batteries for heat production, and nope, nothing.
After a couple of hours, the batteries read 6.3 volts, two days later, 6.3volts.
Reassembled, and three months later, three big flashes on test.
Now I have two PLBs, one in the plane, one on the trail bike.
I think I investigate a bit deeper next time rather than rely on on line forums.