Dual motor VTOL tailsitter spinning and backwards tilt

Hey everyone,
A friend and I are working on a tailsitter and we’re having trouble to make the aircraft stable and need some advice.
Basically here’s our progress so far:

Test Flight 1
We started moving up the throttle slowly. Due to our wrong setup of the rudders it fell over in QStabilize.
-So we corrected that.

Test Flight 2
We put the throttle to max. The aircraft started but with a slight tilt on his back, we compensated with the pitch control. But we loose control when lowering the throttle too much and are thus unable to land. we crash.
-We offset the motors a bit towards the back of the aircraft to try an compensate for the angle we got at the beginning.
-We installed larger control surfaces.

Test Flight 3
Again with full throttle the aircraft started with an angle towards its back despite our last change. It was now more stable but it starts spinning like the torque of the motors don’t cancel each other out. We lost power towards the end due to our battery going below 11.0 Volts unable to give anymore thrust. We crash again.

We’re thinking of correcting the following thing
-Offsetting the Motors towards the belly.
-Recalibrating our ESC again since we replaced a motor before the third test flight, although we don’t think that this may be the problem since we didn’t replace the ESC itself.
-Maybe we have to PID tune our aircraft, but we’d have to read up on it in the docs, since we don’t know how it’s done.
-Definitely fully charge our batteries.

So are we on the right track? Do you guys have any advice to what could solve the backwards tilt and the horizontal spin?

Any help would be much appreciated, and please reply if you need our flight logs or hardware details.

You will certainty need to tune.

If you post logs we may be able to give some pointers.

2021-12-22 16-31-53.tlog (657.2 KB)

Thank you for the quick reply here’s the log file.
The flight starts about 2/3 in.