What to check.
A Fail Open release is like a Maglock it requires 12v DC to keep it locked.
The Power supply is usually 12v DC and may have battery backup in it to maintain security in case of a power cut.
Corrective Action
Check output voltage, replace power supply.
Additional notes
PSU-12v2A
BATT-7AH 12v 7Amp Hour
BRDG-RECT
Links
https://www.entryphone.co.uk/shop/productdetail/PSU-12V2A
https://www.entryphone.co.uk/shop/productdetail/BATT-7AH