GFTR (GFCI) Problems

Since last year, I purchased and installed a total of three of the SCR-15-GFTR electrical sockets, all of which worked fine until we had a severe storm which knocked out our power for two brief instances on August 16th. We tried to plug a small counter top appliance into one of the GFTR sockets only to find that the prongs (two-prong polarized make plug) would not go into either socket receptacle. On inspection, the same is true for the other two GFTR sockets, and on inspection it appears that a white "shield", presumably a child safety, has been engaged internal to the socket. Interestingly, I can install a three-prong plug into the sockets but am unable to find a way to "reset" the sockets so as to disengage the apparent safety feature to allow two-prong plugs.

I would very much appreciate any help with a solution.

Thank you.