I have had my indigo 2 since when they were new. In 2018 after being storage it needed a new battery and had some crackling in the audio.
I contacted access who responded saying they hadn't heard if this issue and no longer had parts. I took to an official access repairer who said the main board needed replacement and no longer available and offered to dispose of the virus for free.
I took it to another repairer. Who had for a few years but was unable to find issue. I found someone online that had fixed 5 with similar issues to mine and was sure it was the dsp. When I got the virus back after pandemic it was real bad. Harsh noises and sounded terrible. A replacement dsp was acquired and was replaced by a friend.
The virus now works with clean audio but after about 30 minutes audio cuts out. If this is ever fixed I'll post about that too. From my years of research and dealing with this. Serious problems with virus c are the dsp failing or the ram.
Even when mine was at its worst it never had issues with the os or anything it was always the audio.
Hope that helps brings some virus c back to life.