theory, it is the flash partitioning.

I think I have a pretty good theory on what is wrong with programming your device (I just reproed it on a similar device of mine). Some kind soul reported that the HELTEC image works fine on the TTGO LoRa32, but I think that somewhat depends on luck because I think TTGO and Heltec partition their flash somewhat differently. I'll need to make a small script to let you program your device reliably. I'll do that tonight.