I have an old Harmony One remote. The Volume down button has become intermittent. I thought I might be able to fix it by cleaning the contact but when I opened the unit, I discovered that the battery is badly swollen and bulging, though there is not (yet) any sign of leakage. The battery still works fine and shows no sign of losing its charge. The unit is normally kept on the charging cradle. 

The battery designation is Li-ion rechargeable, 950 mAh 3.7 volt. It is the original Logitech battery.

The condition of the battery, not to mention all the warnings on it about explosions, makes me wonder if it might actually be dangerous, and if so, how much? The charging cradle is normally never turned off so the battery is always receiving a trickle charge. With all the current publicity about Lithium batteries spontaneously catching on fire, I am naturally concerned. The nature of our house, and the location of the remote, is such that if it did ever catch on fire in the middle of the night, we would probably be goners before we even heard the smoke alarms.

So how bad is this? Apart from that, how difficult and expensive is it to find a replacement battery? Are they even still available? Any help would be much appreciated.