Does it need updating, its memory card cleaning or a factory reset even?
Really, I have no idea. I didnt know it had a memory card.
If it happens again I will look into those things.
Edge 200s are VERY simple... They DON'T have memory cards and are not 'smart' so do not need resetting!
It’s what Garmin do

Every Garmin I’ve ever had ( Etrex, Oregon, Edge) has done that at some point. Battery connection and vibrations are often cited.
Etrex models definitely do/did that. My ancient Etrex H used to switch itself off when I cycled over bumps in the road. The reason is that there are internal battery connections using wipers onto the PCB. They can bounce for a split second and Garmin (in their infinite wisdom) had not thought to include a small capacitor to hold the power line up until the connection remade. Those GPS units have AA batteries inside and the problem seems to be that having batteries bouncing about is not a good idea. I managed to almost completely solve the problem by wedging the batteries firmly in place with a small piece of Blu Tack.
I would be surprised if the battery in an Edge 200 isn't actually soldered in place so bouncing batteries/terminals would not be the problem.
I just did a quick online search and one review mentioned that the device will switch itself off some time after you stop recording a ride. It is a power saving feature. My guess is that you either forgot to start recording, or accidentally stopped!