So not only, zapping 3.3V module with 5V and solder bridges but also …
We don’t say it’s not a good idea, we say they should not be used due to the disruption to the network. And you have to alter LMIC to be able to cope with a SPCF which isn’t trivial.
Please disconnect immediately and read: Single Channel Packet Forwarders (SCPF) are obsolete and not supported
If you want to make some progress, get a TTIG for a gateway and buy a board supported by LMIC-node. I’d normally recommend the Adafruit Feather M0 with RFM95 but in this instance, as it requires some delicate soldering, maybe best to pick something else. 