I have a coleman emerald 455 hot tub and I have managed to lock the electronic control panel. How do I unlock?

All the manuals are here Riley.

https://www.google.com/search?q=morgan+spa+owner%27s+manual

How to lock and unlock your keypad? - Tubs Parts

https://www.tubs.parts > how-to-lock-and-unlock-your-...
Locking: Press and hold the "Down", "Scroll" and "Up" keys simultaneously. The LCD screen will display "Hold the keys to activate the lock". Keep holding down ...

try this link OASIS HOT TUB SAUNA How To Reset Your Spa Hot Tub Heater

Panel needs to be in the display of "Time" 1st. If not, push the "Prog" button to get there. Once the Time is displayed, push & "Hold" the "UP" button for at least 5 seconds. The Lock icon/symbol will be displayed - panel is locked. Release and hold the UP button again for at least 5 seconds, the panel will then be unlocked.

air lock maybe?

You have engaged the system lock by pressing the lock key on your control panel. You will now have to either enter a code or press certain keys in a certain sequence to unlock the system. If you still have the manual for your system you will want to lookup locking the system to see what the default way to unlock it; if you don't have the manual you will have to contact the place where you purchased the tub from and have them tell you how to unlock the system. You might want to try and power down the tub completely, wait at least 1-2 minutes, then turn it back on. It's possible that the system might reset itself and your control panel will unlock.

Chuck, did you find the manual? If not I have one with my spa maybe I could copy it for you.

Ron

Here's what worked for me

Press and hold the following three buttons in sequence: PROGRAM - MODE - SET DOWN. Once all three are being held down, the lock symbol will disappear; and the control functions are unlocked. =0 )

Usually in sequence... Program-Mode-Temp Down... Or temp Up to lock

see if unit has a water level switch