Hartke HA3500 DI/Effect loop question

[Sisbon]

Hi guys, another annoying first post requesting help!

Our bassist recently had his Hartke HA3500 topple off his speaker stack, fell about 5ft backward. It was being DI'd at the time so the XLR plugged into it took the brunt of the force.
The amp still produces sound, however its "farty", distorted and with no sustain. Like a crap fuzz pedal with a low battery. This is regardless of which pre-amp is used, or which input is used.

Upon inspection, the DI/effects loop circuit board is broken, snapped in half. Everything else looks to have survived the fall and I cannot see any further broken connections.
My question to you guys is if I could simply remove the DI/Effects loop part of the amp 'cos we don't need it and can work around it. I wonder if the lack of proper connection at that section of the amp is causing the terrible noise it is now producing.

Here is a picture of said amp:
https://drive.google.com/open?id=182...gUu-TSK5RZQcIi

And here is the schematic of the amp that Hartke sent me upon request:
https://drive.google.com/open?id=16Z...0uP8kSKJl5zyn6

Any help/insight/guidance greatly appreciated. Our bassist has been suitably shamed.

[doombass]

I'm not qualified enough to say exactly what the buffer IC is doing on the send/return-board, but the way I see it you can disconnect the connector CN401 and jumper the send and return terminals named "SE" and "RE" at connector CN401 on the board. That is probably what causes the problem with your signal. Also you can disconnect CN403 and CN404 which go to the DI.

[The Dude]

I would start by gluing the broken board back together and rebuilding/repairing any broken traces.