UT139C repair

[Falkra]

Hello, 

I have a Uni-T UT139C and I am trying to repair it.
It is faulty : it beeps continuously on every position of the contact switch and the display has every segment ON or does not display anything at all (but the beeping continues).

I reprogrammed the 24C02A eprom with factory code (it was modified, probably with a hack that went wrong) using code from this topic, using an eprom programmer).

I checked for shorts and found Q2 Q3 Q8 and Q9 diodes are shorted when on circuit. Out of circuit they check good. Removing all four didn't clear the short on the motherboard.
C16 cap is shorted when meter is set to OFF using selector switch, but not when ON. Contacts of the selector switch are clean and I cleaned them, same for the zebra strip screen contacts.
Pictures (not of mine) can be found here : https://lygte-info.dk/review/DMMUNI-T%20UT139C%20UK.html


I'm a hobbyist, and I'm making progress, I unsoldered and resoldered the SOT-23 diodes correctly with an iron (no hot air this time) and that makes me happy, it's the way to learn, trying on inexpensive stuff. 

I'm thinking maybe the main chip/cpu is dead.
But I don't now how to check this. I'm looking for clues.