Yes, you will need to do a new installation via the toothpick method. My method was I used a Linux VM to format my SD card as EXT3 with a label of LIBREELEC_DISK. I then copied the files from the new install ZIP file to it and used the toothpick method to install. I left the SD card in to boot, it boots up LibreELEC and Kodi as expected, but this is the SD card version and not the internal memory version. Enable SSH and connect to it, then run the tune2fs command specified in the first post. Power down the MX2, remove the SD card, then power on again and it should boot up normally.
I tried looking for a reliable tool to format an SD card to EXT3 via Windows 7+ but could not find one so a Linux VM (with Ubuntu) was easier.
So to summarize:
1. Use a tool (or Linux VM) to format an SD Card using EXT3 and label it LIBREELEC_DISK
2. Copy files from new install ZIP to SD Card
3. Install using toothpick method
4. Leave SD Card in and let Kodi start
5. Enable SSH, connect from a computer, run tune2fs command
6. Shut down MX2, remove SD card, power on again