I reckon I got quite lucky and got mine flashed 1st shot just using the ttl adapter for power. I mostly followed your method. I was connected to my HA server (old laptop).
I thought I’d take some flicks to contribute to making the flashing easier to follow for others.
I managed to flash using only dupont cables and pin headers. No soldering or even clips! I had these but they were no good for gpio2 so I abandoned them.
TTL / UART rig.
Rig for pulling gpios
Shove it all in and use a bit of gravity or slight hand pressure to help with contacts.
I toggled power via usb stick with one hand while the other hand held in gpio2
More details…
BTW, you can extend the life of your filters by adding your own disposable “pre-filter”.
