People are having issues when testing LE and then testing other OS's on the AMLogic platform. They are been advised that they need to reinstall Android firmware after the Uboot is altered on first boot. This is absolutely unnecessary and very poor advice as it is a complex process to restore the original Android ROM assuming you have it.
Fortunately AMLogic is wiser than this advice and they have built in functionality which allows you to boot a self contained OS off a SD card and this will restore the necessary boot functionality to whatever is needed to operate the OS.
The simple method is:
-create a SD card with whatever OS you want to run using the LibreELEC.USB-SD.Creator tool (or whatever tool is recommended by your chosen OS) from the full OS image (not the update .tar)
-insert the card into your SD slot with the power off.
-Press your boxes RESET button and insert your power cord and hold the reset until the first splash screen has loaded. The RESET button is usually in one of two locations 1) at the back of the AV socket 2) in a hole on the bottom of the box labelled RESET. Use a toothpick or a match. A few very rare boxes have no RESET button and for these you will have to use a different method.
This has forced you box to boot off the SD card and has run the aml_autoscript which comes supplied with the OS image which sets up the uboot to whatever is needed run you chosen OS on next boot.
Do this every time you want to switch OS. SIMPLES.
If this fails for you try it again as the reset detection can be twitchy. There are also a number of other techniques which can be used if this method fails.
With this knowledge you can safely test whatever OS you choose without reinstalling any firmware or damaging you internally installed system.
Hope this helps.