There are several hardware limitations to software versions you can load. Look at the motherboard of your CEM+. It will either be a green board or a blue board. If it is a blue board, check the revision on the sticker shown below circled in red.
- Green boards can take any software version.
- Rev.E and earlier blue boards can take any version 2.0 and higher.
- Rev.F and higher blue boards should NOT be loaded with Vsn3.1.0 or lower as there is a voltage measuring glitch that could come up intermittently.
- Rev.H and higher blue boards can ONLY take versions 3.1.2 and 3.1.3. These will have a sticker stating as such (shown above circled in yellow).