Without being disrespectful, it seems like the diagnosis required may be a bit beyond your level. Knowing 'where' to look is just as important as 'what' to look for.
It's difficult giving advise in this 'remote manner', as a fundamental knowledge of how a circuit (any circuit) is arranged will get you more than half way to identifying the possible problem areas.
That particular device could easily be pre-3V3 vintage, but you could look for the power supply stage (inj and out), and the +Vcc pins on major chips to see what's happening there - but one slip of the DMM probe can easily turn the whole device into a 15 year old paper-weight.
Finding +5V is good, +17V seems a little high, (maybe 12V x1.4 = not unreasonable). +1V2 to the back-light could be averaged PWM for a dimmable back-light - hard to tell without a scope.
So the next thing may be to see if you can find any 'clocks' or data running around the major logic chips.
Don't be afraid to step back and ask someone nearby for physical help...!