Pumps failed and possible ACB fault?

Sorry for the long story........


I had a plumber in on Saturday morning to fit a towel radiator in my en-suite in lieu of the small radiator.   In preparation I powered off the Boilermate 2K using the spur switch provided, turned of the F\E feed to the tank, and then drained all the hot water away from the thermal store using the drain valve, and then drained down all the upstairs rads, as thats where the new towel radiator was to be fitted.  

That was all completed without issue and the plumber completed his works. I then started closed the drain valve, opened the F/E valve to start the refilling process and after some time started bleeding the upstairs rads.

I powered on the BM2000 and noticed the single green LED near the top of the unit\clock didn't light up (which I thought was strange as I'm sure it did previously), and also the red LED display didn't illuminate, which again I'm sure it does at the initialisation stage. There were 3 green LEDs at the bottom of the ACB.
The Heatmiser digital stat in my hall was showing calling for heat, and I let everything run and expected the boiler pump to start running and the boiler to fire up. It did eventually after around 30 mins.  The LED display started to display On with the two lines. The rads started to get hot and all seemed good.

After about an hour the stat was still calling for heat as the house was still not up to temp, but the rads were cold.  The middle pump (Rads) on the BM was scorching hot and I opened the bleed screw and steam came out!  I took a shower and the water temp was fluctuating between normal heat slightly cooler.

I took the pump bleed screw out of the middle pump and to check it was moving and it was really tight, suggesting it had seized somehow. I switched everything off and left it until the next day as I was going away for the night .

I came back the next day and removed the left and middle pump heads from the system and stripped them down and cleaned them up using wire brushes etc to get them as clean as possible, and refitted them, swapping there position on the BM. The pump that was stiff seemed still NOT to be able to move freely when re-installed into the pump housing. I removed it again and checked it was still able to operate by hooking up a 240v wire harness and the impeller wouldn't spin, even with the me flicking it to start it, so now figured the electrics must be fried\toast. The other pump (originally the boiler pump but in the rad pump position) start making a distinct ticking sound when in use, which suggests it's terminal too.

I've bought a couple of UPS2 to replace these two pumps, the question is are these 100% compatible with the Grundfos UPS 16-50 x18   P/N 59525452 which were previously fitted as left and middle pumps?  From reading on here, there are a few posts stating that the DHW pump must be replaced by the exact same UPS 16-50 x18  pump, but can the Boiler and Heating pumps be replaced by the UPS2 without issue?

Also, pressing the SW1 or SW2 doesnt show any info on temps, so does this suggest the board is fried somewhere?

Thanks

Board
Grant from Scotland?
If so spoke to you on phone

Mike
MGC/H2O
Norfolk

Yes Mike, all up and running thanks to your assistance, much appreciated :-)