Tektronix DPO2024 Needs help

[晓看风云]

I have a Tektronix oscilloscope DPO2024 that needs to be repaired, and it has always been very normal. Suddenly, one day, it started reporting errors and could not self calibrate. Every power on self test can pass, but when entering the system for self test, an error was reported, and I didn't understand what this error meant! Has anyone been exposed to these issues? If I don't perform self calibration, the waveform can be displayed on the screen normally, but after the self calibration fails, there will be no waveform left. If I turn it on again, it will be like forgetting the self calibration failure, and it can display the waveform normally! I have tried to open the channel acquisition module, but after rough measurement, it seems that everything is normal. The problem may be on the self calibration line. Can anyone provide some suggestions? Thank you very much！！！