There is no flash limit on ME7.1. All you need to do next is to pull the ECU, open it, put it in boot mode, read the file and compare to the last one flashed, check if there's any significant differences. Then flash either stock or the previous tune in boot mode and you're good to go.

I recommend doing it on the bench instead of in the car.
From my experience, I either ground pin 24 before connecting power or shortly after, it depends on the ecu. Also, nothing needs to be soldered if you have some fine multimeter probes or similar.
Please note that bootmode flashing is not supported in Nefmoto AFAIK. You need MPPS/galletto for that.

You can use the ft232rl cable to boot mode flash it, galletto 1260 will work fine, you need to use mprog and change the serial in the cable and it works fine

Could you elaborate a bit on changing the serial? I will look through the forum in case there is another post explaining this. The cable I have is the blue VAG KKL cable.

Hi again. Over the past couple of days I've done the following:
 - Removed ECU from car, soldered a wire to pin 24 for boot mode. I realized i had soldered the wrong wire before so hopefully i didn't damage anything.
 - Bought MPPS v18 clone cable from amazon that also came with an obd harness to hook up directly to ECU. (Checked all wires and they match the necessary pins)
 - Bought an adjustable power supply that allows me to provide the right amount of voltage and amperage.
 - Downloaded and modified Galleto to match my KKL cable serial.

As a reminder, my ECU is ME7.1 part#4Z7907551L
The car is a 2002 Audi Allroad 2.7t 6speed manual. Note, the car was flashed/chipped by previous owner but I have no info on what was done as I got the car from a used car dealer.

Now back to the problem. I have attempted repeatedly to get this damn ecu into boot mode but it has failed every time.
Boot mode process as follows:
 - Hook up OBD harness to ECU.
 - Connect OBD port to either MPPS and use MPPS V18 program or Vag KKL for galleto 1260.
 - Connect to power supply. (Luckily the harness has a switch for power thus allowing me to use that instead of disconnecting/reconnecting to PSU.
 - Ground pin 24 before switching power on. Voltage set at 13.5. Max 1 AMP.
 - Turn power on and disconnect pin 24 ground after 5 seconds (as per Galleto)

I have repeated that process while holding ground for 3,5,8,10 seconds but no difference.
MPPS Shows ECU not found, even though it recognizes the voltage.
Galleto states ECU Boot Mode Inactive.

I don't know what else to do here, other than to start looking for a new ECU.
If I've missed a step please do let me know.
The processes I followed were based on information I found in the forum, rather than asking how to do it, I opted to do research first.
I have looked through the forum in case there's anyone that had the same problem, but everything I found was for ME7.1.1 which is different.

Any help is much appreciated. I will make a separate post with links of the equipment I bought in case someone is looking for a similar setup.

I grounded the third pin instead of the second on the chip. I'll try to find what the purpose of that pin is and then maybe that will tell me if there's no point in going further. Assuming that there is no damage, can you specify which resistor needs to be removed. I'll look it up, but there's a plethora of pictures from people that show variations of ECU's and i don't want to make a mistake again.
Thank you for your time.

Thank you very much for this. In regards to the MPPS, no I did not. I have read that some people use either a 1k or 2k resistor on the ground lead for pin 24 as well. Not sure if this is necessary but i will try. I tried bridging the pads as well with no luck. But this was without removing the 0k resistor. Additionally, the amperage varries between 0.185 to 0.230.
Also I did some browsing and found the data sheet for the chip. The pin I grounded originally was pin 25 which on the chip translates to DQ12. I have to look further to figure out it's purpose but from what I read it is meant for data input/output as pin 24 (DQ4). See attached picture of the chipset diagram and data sheet file.