[Puck] Unable to connect. Device became undiscoverable from both Macos and Android

I've reset the device many times. Shouldn't it clear any pairing/bonding information on it?

Yes, when you hold down the button all the way through the red blinking it will delete any pairing data.

I believe the bootloader is working fine. It's just a newer bootloader on the new batch of Pucks (which it seems like you have - I'll update the documentation). The green LED should get slightly brighter when you release the button?

Could you try the steps outlined for the firmware update? nRF Connect should see a DfuTarg device and when you connect the light should go from green to blue. If you can do that then we'll know Bluetooth is working ok.