PSP Not booting into Service Mode

So about a year ago I made a Pandora Battery + MMS, and I remember it working fine, I could downgrade back to CFW from 6.20 official, and it just worked. Yesterday I charged my PSP that I hadn't touched in months and tried to boot into Service Mode to downgrade, and it's...just booting normally.

The guides I checked said to hold R during bootup, but that didn't do anything. One of them said to hold up on D-pad, that didn't do anything either. I remember it was some sort of combination, like select+R during boot, but that didn't work, start+R didn't do anything either.

Do I need to re-make the pandora battery or something? Is that even possible on official firmware? It's currently at 6.20.

Nevermind, I got it working...apparently holding Start+Select+L+R is the way to activate the Pandora Battery / Service Mode.