This is a problem with the batteries – when there is too much force on the ends of the AA batteries they can be damaged internally and heat up. This can happen if the battery contacts in the meter are bent so that tightening too hard on the screws pushes on them and causes excessive pressure, or if the meter is dropped right on the battery end on a hard surface.
If you change the batteries, the meter should be fine. If it happens again, I’d examine the battery contacts to make sure they are not irregularly bent.
Regarding the original batteries dying in the first place: Were you a crowdfunding backer? The first batch of meters to leave the factory had a firmware bug that reduced battery life substantially. If you run a firmware update, your new batteries should last over a year.