My device doesn’t work at all with thezambezi_v6a.img or the v5a_zambezi.img blobs.
It completely freezes after maybe half a minute, every time, with high battery drain (device gets hot and battery is significantly lower after a reboot). It doesn’t freeze on security code input.
V5 seems a little bit more stable, but not stable enough to even install the first app from the jolla store.
Flashing v4 seems to result in a stable system, although it has only been 2 minutes or so, so far.