You might try cleaning the battery contacts with something like Deoxit or isopropyl alcohol in the case that the contacts have become a little dirty. You might also be able to try very gently bending the spring steel that pushes against the battery a little but I would be very cautious about trying to bend it more than only a small amount least you risk pushing it past its elastic limit and breaking it.
If nothing works and you want to reduce the annoyance a bit you can remove the toast message that can be done with a custom keymap. The is a keymap for doing this listed at the end of my long-press keymap guide here…
Do note that there is no way to get the remote to not send out the F2 key when it thinks the battery is low so it is going to still fail to send the button pressed whenever it is popping up the message now. The keymap I posted will only prevent to on screen message from being displayed.