So I just took apart my multimeter, tested resistance of the Piezo and it did not show anything.
Removed the piezo from the PCB and tested the diode continuity, nothing. As you can see from the pictures, it does not look like anything went wrong with my BM235.
I had a Piezo lying around and replaced the original, and voalá, started beeping again. Probably the replaced Piezo does not have the same rating form the original, so I'm not sure that it is a smart decision to keep it there, it definitely does not sound like the original.
I'm attaching a image of the original piezzo, do you guys know where can I find a similar one?