All - reaching out to the collective intelligence of the group to try and figure out how to resolve fault codes on my 2009 Audi TT... I recognize some of these issues have been handled with other threads, but can't find my case specifically, so appreciate in advance any thoughts or leads... post is long, but want to be as complete as possible on the background.

Plenum drains clogged and water overflowed into the fresh air intake, into the cabin. Unfortunately this was while we were out of town for an extended period... some friends emptied the water from the inside, etc. The vehicle still ran fine, no fault codes coming up. The car sat for awhile longer until we got back to town. By then the battery was completely dead - no electronics kicked in when starting it. Charged the battery to the point it could start. Cleared the plenum drains and checked the AC condensation tube to ensure it wasn't the culprit (it was fine). Then the fun begins with working out the multiple fault codes.

First error code - low voltage. Charged the battery fully and cleared the code using a code reader. Error hasn't returned.

Second - low tire pressure. They were low, aired them up, went for a spin. Reset them. Fault cleared and hasn't returned.

Third - fuel system malfunction, and gas gauge on E, although tank is full. I've read this may be the fuel sending unit. Odd that it failed at this time. Can't get this one to clear. Have driven the car around a bit, filled the tank, check every single fuse in the car, issue persists.

Fourth - HVAC blower motor doesn't work. Checked fuse (was fine). Removed glove box (Airbag fault is now on, but I understand that one is due to glove box removal) and removed blower motor. Spins ok, not seized. With car off, voltage at the blower motor (not the resistor pack, but right at the motor) is 0V... makes sense. WITH FAN SPEED OFF - when ignition is turned, goes to about 11V. When car turned on goes to 12V. Fan setting is still at "off", but be motor is seeing 12V. As fan speed dial is turned up from "off" to max setting, voltage at blower motor is still 12V... no change.

Confused by this blower motor behavior... with switch at off setting, it should be 0V and as fan speed dial increases it goes up to 12V.... any ideas on if this is normal, or what it indicates has failed? I don't want to buy a new blower motor assembly to find out it is something else acting up.

Fifth - passenger seat won't adjust (forward / backward etc). Haven't looked at this one yet.

With the above background and detail, looking for recommendations - is the blower motor behavior normal, does it conclusively indicate I need to get a new one, or should I be taking the car into the shop to get all fault codes cleared and see what retriggers before I go about diagnosing and replacing individual components (blower motor, fuel sending unit, seat adjustment motors), hypothesis being that the low voltage issue triggered all of these and now they are just stuck in that mode until there is a complete system reset?

Thanks all for any insight...