My Soundlink Mini 2 had a problem where, if I had left it a while and despite their being plenty of battery, it wouldn't switch on unless I connected it to AC power source.
After searching on the internet I concluded that it was going into "shipping mode" as described in the following link: https://www.reddit.com/r/bose/comments/3klkwj/soundlink_mini_ii_wont_turn_on/
I followed the suggestion to update the firmware. Unfortunately, whilst updating (at least past 50% complete), it suddenly said the connection to my device had been lost. I tried to update again and again repeatedly and the same thing happened each time (although now only after a few % of updating).
Having spent a fair bit of time with all this I decided the problem wasn't so bad that it was worth the trouble and disconnected from my computer.
Now the thing won't turn on even after I've connected to AC power. All it does is show the orange battery light. If I press power it either tells me what the battery level is or it does nothing. It won't connect to my phone/computer via bluetooth. It won't even play through an aux cable.
I have tried the reset where you hold the multifunction key for 10 seconds, the lights are blinking, I disconnect, release the button and then reconnect. Doesn't work.
I've tried the factory reset where you hold the power button down for 10 seconds. Nothing happens.
I've gone back to trying the update using various cables, again it says it disconnects after 6/7% updating.