In my card (stock Vega 64) the main BIOS was at the “front” (video connectors’ side) and the backup is at the “back” (power cables’ side). But that isn’t important. The good thing is that the flashing was successful. Also, the fact that the secondary BIOS is locked is one of the best secondary features of Vega (and I bet other Radeon) cards, especially Vega 56 ones! For the HBM, try 1100MHz, that’s a very good increase from the 56’s 800MHz and it’s one of the easiest to reach with full stability.