SRAM Guide brake lever won't return
This is typically caused by seals which have become soft and sticky due to contaminates like degreaser.  It also happens over time, and SRAM Elixir brakes are especially known to have this issue. 

The Guide series hasn't been bad about this so far. 

The solution is to replace all the seals in the lever.  SRAM has a special grease (Avid DOT Grease) for this purpose, or you can use DOT 5.1 compatible grease.  Regular grease will damage the seals.