Red Triangle and HV Fan from plugging in OBD?

As title says, I plugged in my laptop the other day (didn't even have techstream running) and instantly the red triangle appeared and the HV fan kicked in. I disconnected the 12v and that cleared the lights, I didn't stay connected long enough to read if it did have a code.

I've had OBD trouble in the past, with the red triangle appearing after connecting a cheap bluetooth OBD2 adapter (which works on another Prius) but the HV Fan coming on is new. It wouldn't surprise me if my current issue relates to a cheap mini-VCI cable being cheap, but I'd still like to work out why my car doesn't like having things connected to the OBD port. Does anyone have any ideas what could be causing this?