Ive recently got a used tyros 4 and its developed a fault some of the buttons have stopped working including on the front panel G And Exit on the left side auto fill in intro 3 variation 1 entertainent and swing style select the fault is intermitant and rights itself sometimes. Ive re installed the firmware and stripped the tyros. Checked and re seated the cables.

Sounds more like a hardwareproblem rather than software issues.
Maybe a loose cable or two, and/or bad solderings?
Take a look inside the T4 to see if here is some tips & hints to help you out:
https://www.youtube.com/watch?v=iaxE4i9x_S4

... or if there is a dealer / repaircenter near by to ask for help?
Good luck, T4 is a great keyboard as long as it work as it should.

Ive opened it up looked for loose cables took out the left board which seems to have most of the problems nothing obvious. I also ran the test routine as mentioned in the service manual.

call the ex owner see if he had the same issues?.....hope he didn't know about them before he sold it and didn't say anything?...good luck hope you get it remedied asap somehow or serviced in shop..

Well since I stripped it down and re seated the cables it seems to be ok.