HELP - I've totally messed up

[Princy557]

Hi all,
Sorry, it’s me again.
I’m in a mess. First some history. I bought an A20T, I had problem after problem with it. I’m in touch with the support team but we were getting nowhere fast (I should say slowly very slowly). This started way back in December 2021. I am disabled and have spent a lot of time NOT able to get to the machine. So say in January I was in so much pain I only got to the office 7 times. Same for the following few months as well.
I went through three hotends during 3 months. Each of which I bought, due to there being a 30-day delay from anything sent by support. The motherboard was replaced, thermistors replaced plus heaters and other stuff.
As I had bought various addons for A20T, I decided to give up and buy another one, yes another A20T. I would at least have spares etc.
It arrived and has been built. After the first few days of set up and preparing for use, I managed to print a funnel. Decided to print another with a quality change (not so coarse). 15% larger. It failed, messages I’d seen before like head too cold, but it tried to continue printing. So the usual reboot everything and off I go again. ’Lego’ brick this time. A ball of string was the result. Let's try again. Bang there it was again. The same errors as the other (first machine)
Heating failed
Printer Halted
Please reset

That darned message I’d seen so many times previously.
OK enough of the woes.....
I seem to have got my mind in a bit of a jumble.
Can someone please lay out exactly all that I need to do with a new 3D printer, Cura 5, and assorted required (A20T) setup changes..
Where to find the files would help as well. I followed a link today, the same question was to find the firmware. I found three or four different paths to follow, all with different outcomes.
The machine gives me the following information.
Marlin: 1.1.8
Baud: 250000
HW Ver: Gt2560 V4.1
FW Ver: V2.3.2

Anyone with time to spare lead me through it, please?

Regards
Princy557