Yamaha CVP205 dead mother Board (DM)

Hi All,
I scored a CVP-205 Digital piano - possibly the main board gone and had one wonky key.
Have fixed the Key and I have the workshop manual for the whole Piano so all the parts lists and schematics.
My hobby is electronics so I’m not afraid of attempting a repair on the board at circuit level - I’ve cross-referenced the large controller chips and can source them - ROMless CPU/MPU’s but should i go through and do the SMD caps first before the 168 and 208 pin 0.5mm pitch SMD chips?

I know I can send the board overseas and get it repaired (live in NZ) for around $800 but even the chips and the caps won’t cost anywhere near that…
Why is it so hard to repair these boards?
Rest of the unit is in absolutely immaculate condition.

Anyone had any experience in attempting this?
Be interested in anyone’s thoughts / input.
Kevin NZ

You mentioned you have the Service Manual, so that’s half the battle. Next, take your time. You also said possibly the Main Board is bad… What are your symptoms? No display? No LEDs with the buttons? No sound? I would first check the voltages from the Power Supply to the DM PCB. Anything seem low? Disconnect connectors from the power supply and recheck the voltages. Are they correct now? If the voltages changed, reconnect the DM board, and disconnect everything else from the DM board. Voltages come back up?
Look at the capacitors on the DM board. Do any look swollen? Does the DM board smell like a fish market? These are indicators of bad caps. If you feel confident, I’d say go ahead and order, and change the caps. (Practice de-soldering and soldering on some junk first and watch some videos. Use the smallest solder tip you can get.) The only ICs I’ve seen go bad on the DM board are the DACs and the IC right after the DAC (IC27 & IC31). More specific symptoms will help.