In this study, the post-annealing process of garnet-type electrolyte films produced by the powder aerosol deposition method was optimized by utilizing high-power LEDs. The post-annealing time was greatly reduced from hours to several seconds. The film conductivity at room temperature could be increased by three orders of magnitude from 5.0 ⋅ 10−8 S cm−1 to 5 ⋅ 10−5 S cm−1. For the first time, the required energy for this almost complete conductivity restoration could be quantitatively estimated.