hi @Noraseth , ah, see what you mean now. Just tried within CCW myself and it looks like you can't replace the default PSU with the upgrade SKU. Reach out to your Meraki AM and see if there's anything they can assist with.
You can do it with a 3850 or 9000 series switch so why not with the ms390. let us know how you get on.
Darren OConnor | doconnor@resalire.co.uk
https://www.linkedin.com/in/darrenoconnor/
I'm not an employee of Cisco/Meraki. My posts are based on Meraki best practice and what has worked for me in the field.