rPi zero lipo shim hissing sound

Recently I started encountering a problem with the Raspberry Pi zero lipo shim. Randomly after few minutes the shim starts making a hissing sound and the rPi shuts off. This seems to occur after I start making a video recording with a Pi Camera, but it’s hard to pin point exactly what triggers this. Sometimes the sound starts as soon or few seconds after I start the camera, sometimes after few minutes. Sometimes the hissing sounds keeps occurring even if the lipo shim isn’t connected to the rPi at all. It started occurring when I was trying to power 2 rPis at the same time using the same battery. It worked fine for a while but now the hissing happens fairly consistently.
Would anyone have a suggestion about what causes this problem and how to fix it?

It’s only rated for 1.5 A max, sounds like you may have exceeded that and damaged it.

Thanks. Could 2 rPi zero really draw 1.5A? Each had a camera and one was powering an LED, but that was it.

Hard to say, definitely. That’s my best guess.
Raspberry Pi Documentation - Raspberry Pi hardware

I think you might be right. What is odd is that it worked fine for a long time. The only thing that changed, as far as I know, is the python code used to make the video recordings. So it would mean that this code leads to an increase in current large enough to burn the lipo shim. That’s strange.