"" no codes to start but 2BAA (particle filter full) code now appeared and will not clear, ""

Live data values for the above please and DVM / Scope Voltage readings from DPF Pressure sensor at KOEO and idle.

DPF faults would normally clear at Ign on and usually at idle ? What do you get with Pipes pulled off DPF Sensor ?

Pressure guage in place of upstream 02 will confirm a blockage.

Assuming this had no Engine issues before you removed the gearbox ??

Also - there are reports of these cars being non starts if the the 2 mating surfaces (bell housing and Block not being polished clean) Apparently causing noise on CKP) Well documented on iatn and known to Volvo Technical. Reading tells me that attaching a big thick jump lead between Engine and Gearbox does NOT fix it,

Hope that helps