www.makemkv.com

Today I was prompted to download a new firmware, my play at time is a little flaky so I installed it hoping it would improve but now it will not play MKV files. The picture is completely turned off but the audio is working. It does not appear to be reversible.
Anyone aware of this? Hopefully a new firmware could be made to reverse this.

Not an Oppo owner, but there's a section in this guide about jailbreaking that details a way to revert to old firmware: https://www.avforums.com/threads/free-o ... k.2332399/

It doesn't appear that process requires the device to be jailbroken, but it does still seem pretty involved.