QQ190 – Motors continue to accelerate even when throttle is low.

Hi QQ. I flew my QQ190 for the first time in about a year the other day. Just been sitting on the shelf. When I arm my motors and select my usual flight mode (airmode/antigravity/horizon) and go to take off, the motors start to accelerate as normal, but then keep accelerating despite my throttle position. eg: if I aim to hover, it will start to hover then very rapidly keep accelerating skywards – the only solution is to drop my throttle to 0 or disarm the motors. I literally need to let it fall to the ground. This happens in all modes (acro, etc.). Prior to this, it flew like an F-16 on rails. I have recalibrated the ESC’s a dozen times, calibrated the accelerometer and re checked all other settings (PID’s etc). In desperation, I updated to the latest Betaflight Calibri_Race 3.5.0, tuned it (without issue) to fly as previous, hoping the upgrade might somehow solve the problem, not so – issue remains. I don’t think it’s the ESC’s as they calibrate fully and successfully on all motors, the motors are pretty much just slaves – could it be the FC signal to the ESC’s?? What confuses me, is that no changes or events happened to it between successful flying and this problem – just time on the shelf. Can I replace the FC in the powercube – could that be the issue. I’m assuming they are still sold and will just slot in place in the powercube – would rather not, but I can’t think what else could be causing this. Any advice much appreciated. Cheers. Jeremy