The Mk1 Q7 has a few common issues which are caused by water ingress, water not draining out where it should, or electrical connections losing good contact.

Here’s the preliminary checklist I wish I’d had when I bought my Q7…
Shopping List:
Set of plastic pry-tools.
Q7-suitable low-profile wiper arm puller.
Fuel filter.
No.10 triple-square/spline bit.

Water Ingress Damage Inspection:
Behind right hand side-panel in luggage compartment.
In spare wheel well (remove wheel).
Behind fuse panels at both ends of dashboard.
Under front left seat (tip seat backwards as per battery replacement procedure, ease up carpet and look underneath).
Plenums at base of windscreen (even if you’re familiar with VW/Audi, it’s worse on the Q7).

Water Drain Checks:
Perform inspections above first.
Front right plenum (add a pint of water, check for similar quantity pouring out underneath).
Front left plenum (ditto).
Sunroof drains (a garden weed sprayer is useful). Introduce small quantity of clean water to each corner of drainage channel and check for corresponding drips under car.

Electrical Parasitic Drain / Poor Charging:
See water damage above.
Door handle sensors.
Alarm horn.
Engine earth strap under air filter housing (remove air filter outer cover and intake ductwork, remove earth strap, inspect, clean contact points).

Extra to Routine Servicing:
Fuel filter.
Add additional earth strap to engine.

All Audis with Rear Wiper:
Pull off cover over spindle/sprayer jets.
Pull off plastic piece with jet nozzles.
Activate rear wash with jet nozzles removed.
Clean nozzles, blow through to test, refit. Interdental cleaning brushes are useful for this.

There are tons of additional generic checks but the items above are pretty specific to the Q7. Even if you don’t have a sunroof, water ingress is still an issue with the exception of behind the right panel in the luggage compartment.

And one generic check which is unbelievably easy on a Q7 is the A/C drain:
There’s a pull-off access panel in the passenger footwell under dashboard. It has holes in it for fingers. Under the cover is a rubber tube that disappears through the carpet. This can be carefully eased off the spigot and the rubber tube blown through with air or water. With the A/C running, air pressure should be felt at the plastic spigot. Check cover for location of locating pegs and corresponding holes under dashboard before refitting cover.

 

Very nice collection!

IIRC, the bolt used to connect the engine grounds strap to the frame is a single-use, torque-to-yield spec bolt, and that's something to watch out for when DIYing on the Q7 in general also. Lots of torque-to-yield, single-use bolts abound on the engine's maintenance points, and also show up in unexpected places. Check those torque specs prior to diving into a Q7 project.

Useful Q7 links for the new and established DIYer:

https://fuseandrelay.com/audi/q7.html