Even after the 3.3v conversion, I'm running into some troubles when "cold booting" the module, literally.

It's mounted in the trunk and it gets cold in there. When it's cold the WT32i tends to shut down and/or reboot itself. I don't think it's the WT32i's fault, it might be QC issues with the Betz board. When I first got the board, it worked for a while and then one of the Vias stopped conducting current and I had to make a jumper. I'm wondering if that's happening for other connections now, being exacerbated by the cold.

I'm thinking of developing a board to which I solder my own bare WT32i and FTDI UART (for loading the latest firmware onto the chip). I was hoping to avoid SMD soldering but it looks like I might have to bite the bullet.

My question is: How do I solder a chip that doesn't have any pins? I mean look at this picture: https://media.digikey.com/Photos/Silicon%20Labs%20Photos/WT32I-A-AI61.JPG

There are some solder pads sticking out from the edges on the Betz board but it looks like they go tuck under the chip's "base board" and I can't actually reach the contact points, I can only heat up the pads and pray.

What's the correct procedure for soldering a chip like this with no visible pads?