Blues completed the signing of Scarr from Stourbridge in January 2017 for an undisclosed fee.
The central defender penned a two-and-a-half year deal at St. Andrew's.
Just before leaving the non-league club, he had played a major part in the Glassboys' historic run to the third round of the FA Cup, scoring twice in the 'Proper' rounds of the nation's most prestigious knockout competition.
Scarr had initially joined Blues on trial, playing two matches for the Under-23s but an injury picked up soon after his arrival at the Club meant that he wasn't able to build on that tally before the season's end.
Scarr spent the 2017/18 season on loan with League Two Wycombe Wanderers, where he made 26 appearances with the Chairboys, before his campaign was curtailed in March 2018 through injury.