MXQ M10; can't flash TWRP

Hi all, long time luker!

I have an MQX M10 tv box, this was a great box tbh, but only runs Andriod 4.4.1, I was unable to run Kodi 17+

With this in mind I searched for new FW, and noticed that the M8S(+ too?) Seemed the same ref board (info on board says M8 v8_9)

I managed to brick the box messing with different FW, but flashed a FW from Chinagadgets (.img file using USB Burner) for an M8S. This works fine, but it is only Android 4.4.1 again.

I have a zip with Android 5.1 on and TWRP (also from China gadgets!) But am unable to flash the TWRP to install the zip file (just hangs on boot on M8S logo).

I have tried installing the zip in stock recovery but get tge error: signature verification error, after it checks the zip file.

Anyone have any ideas, I have spent hours trawl ing the forum and internet in general and I'm pulling my hair out! Lol. If I could get TWRP to install I think it would then be easy.

Many thanks in advance guys!

Mark