A lot of people have had problems getting BS to install on a thumb. It seems that for whatever reason, the install can be very picky as to the brand. I haven't tried it. I know you got a M1 recently. Are you doing this in case the M1 crashed?I thought it may be the thumb drive , I’ll try it with a normal ext drive next .. thank u
If you type command-L at that window it should bring up a log file which might provide some useful information.I give UP.. I guess apple doesn't want us to install BS on an ext drive... Tried numerous times on a thumb drive and now on a regular WD ext drive still gets stuck .. Im done..