Well I think we are seeing 2 different problems:
1. Sleep. Adapter falls asleep and can't be woken up by the app or the car. Slow blink of yellow power light, can be woken by pressing the button. Could be remedied by running sleep setting ST commands mentioned previously in this thread.
2. Adapter 'hangs'. This happens during use, often during heavy use with lots of can traffic. Bluetooth and power lamp are steady ON, but no life on either car or bluetooth traffic lights. Will not wake up by any command, or button. Only remedy is to unplug and replug.
#1 I believed to be a very rare occurance, only seen on LX adapters, and only a very narrow batch sold several years ago. 2 users in this thread had it, managed to fix by changing sleep commands. I am still waiting for more data on this, if I am to implement these settings in the app, but thought it was only those 2 people. If you are seeing it now today, please report it to me so we can dig deeper. Try the sleep commands and report back if that solves it.
#2 is the issue I see with all 3 OBDLink adapters occationally, at random intervals. This is the issue OBDLink is now finally working on trying to solve. This was Schubert confirming they are working on it, so don't send your units back yet, let's give them some time and see if they can make a firmware fix. Then all affected users (probably ALL OBDLink owners) could just flash the new firmware and the problem would be solved forever.