Soft, rectangular lipo packs

My son has a DVD player with a rechargeable battery pack that has died. I tore it open and it has 2 soft plastic rectangular packs in it for a rated 7.4v (nominal and lipo, I assume). Don’t see any writing on them. Wired series with an extra wired marked BM on the board (monitor?).

The packs are 30 x 130 x 10.5 mm. One is zero volts and the other is just over 3.7v

The interesting or maybe scary thing is the dead pack is rock hard and the one with voltage feels puffy and is over 50% thicker than the dead pack. The case is hard plastic and is busted out above and below the 2 packs. I’m thinking both packs go to the recycling bin.

Haven’t checked eBay but was wondering if anybody has seen them? And if there are any other thoughts about the puffy pack?

You can buy them from hobby king for cheap, I use them for my remote control cars.

ezarc beat me to it. They've got LiPo packs in all sorts of shapes, sizes and capacities.

Thanks. They are similar to these: Radio Control Planes, Drones, Cars, FPV, Quadcopters and more - Hobbyking

Multicells packs won’t work unless maybe they were side by side. Max width for each is 31mm but longer to around 155mm length would be OK. Didn’t see it here, but will look around some more.

Would be easier to just get one of the variable voltage 18650 4 cell boxes and fab up a connector but I can’t trust my son to not break the connector/cable.

RC helicopters sometimes use LlPos.
Google for safe ways to dispose of the puffed pack.
Phone recycling bins often have puffed cells in old phones.