Accelerometer calibration timeout [APM2.0]

Hi there
After 5 years of break I’ve decided to blow the dust off my APMs. I have APM2.0 for quadrocopter (mounted and ready) and APM2.5 for plane (still waiting to be assembled).
I’ve flown with this quadro back then, before the crash. Now, after all those years after assembly it drifted a lot to one side. Planner shows that horizon is ~10° off so I decided to update all the software and firmware.

I’ve downloaded APM Planner v2.0.24 (previously I was using Planner by Michael Oborne), picked quad, APM2.0 and it flashed the latest firmware that is available for this old board. I went through manual step by step and by “mandatory setup” in APM and each step was successful except one. Accel Calibration. It just counts down until it times out and on main screen in Messages tab I can see:
[MAV 001:1] Place vehicle level and press any key.
[MAV 001:1] Calibration FAILED

The problem is that new Planner does not have console (Views->Terminal shows Config tab) so there is no way to “press any key”.

So after this long entry here comes the main question: how to calibrate accelerometers so I can have straight horizon and fly properly?

PS, I didn’t know which category should I pick. Not sure what is Copter 3.x so I picked ArduCopter.

I’ve run old Planner (APM Planner Mav 1.0), connected, then run new Planner and… this time it worked, so hard to say what was the problem, but it seems to be solved now.