The FBI has the Texas church shooters’ cellphone — but can’t access it because it’s locked, officials revealed Tuesday.

The phone — which may help uncover gunman Devin Kelley’s motive — has been sent off to Quantico, FBI special agent in charge Christopher Combs said.

Phone ​encryption has been a problem for the​​ feds in the past — the Justice Department tried to force Apple to help it access the San Bernadino shooter’s iPhone last year, though investigators eventually cracked it themselves.

“It actually highlights an issue you’ve all heard about before. With the advance of the phones and the technology and the encryptions, law enforcement .- whether it’s at the state, local or federal level — is increasingly not able to get into these phones,” Combs said Tuesday.

Combs refused to say what kind of phone Kelley’s is “because I don’t want to tell every bad guy out there what phone to buy.”