FOR FORDS SAKE!

Hi there. Im a new member here and looking for some help with my 56 plate transit connect 75 tdci.
The problem started last night after using my vans battery to start another vechile that had been sitting for a while. Now the flat battery from the car somehow ended up on my van and when I went to start it obviously didnt start so put my orignal battery back on. The van did crank but did not start! I tried 4-5 times cranking the engine but still no joy and then it stopped cranking altogether.
I have checked the fuses and relays all seem good.
The battery is fine lights dont dim when trying to start. I can crank engine if i cross starter motor terminals but only cranks no start.
The red led near rev counter flashes normaly until i try to start with key which then it comes on permantley it is not flashing fast, it is just on! After a while it flashes twice and then three times am i lead to believe this is showing a code 23?
Im stuck and in a bit of a panic as need van on tuesday as start a new job. You take a working vechile for granted until it doesnt work 😢
any help please!!!!

daytek123

Hi did you manage to fix this problem