Glad you found the solution, sorry I didn’t swoop in fast enough.
Battery death within a few weeks of standby is not normal – If you have a Mooshimeter from the batch that was affected by the battery contact issue (https://moosh.im/2016/09/short-circuiting-battery-problem/) you may have a battery contact that has scratched through the label and is making marginal contact with the battery surface. This was counterintuitive to me but several users have reported it, so if your batteries die within a few weeks again please check the contacts.
Let me know how else I can help, best
PS. Thanks again @Andreas!