THE DARK TIMES
On Skako Minor, Clone Force 99 helped Anakin Skywalker and Clone Captain Rex get behind enemy lines to rescue the clone called Echo, who was previously thought lost in the escape from the Citadel. It was Tech who first locked onto the live signal that suggested Echo was alive and being held captive. His abilities also helped the team to communicate with the Poletecs and tap into a Separatist Dreadnought to feed the enemy bad intel and clinch a Republic victory.
At the end of the war, as the Emperor executed Order 66, Tech and the rest of the Bad Batch did not respond to the inhibitor chip in the same way as their clone brothers. Back on Kamino, Tech and Clone Force 99 were tested by the Empire, which used live ammunition to assess their battle prowess in what was intended to be a training simulation.
After an Imperial mission to eliminate an insurgency of Separatist droids on Onderon -- only to find organic beings just trying to survive -- Tech and his brothers defected from the new Empire alongside a child called Omega, who was a mutated clone like the rest of the Batch. However, Crosshair remained behind to serve the Emperor and Admiral Tarkin.
With the bounty hunter Fennec Shand on their tail, Tech gifted Omega with Crosshair's old comm device so she could remain in communication with the rest of the team should she become separated from them again.
Although Tech tried to warn his brothers about the inhibitor chip implanted in each of their brains -- a failsafe created to turn rogues into mindlessly compliant soldiers -- it wasn't until Captain Rex tracked them down to Ord Mantell that the others fully understood the danger the chip posed. Ultimately, the chips were removed from Tech and the rest of the Bad Batch on Bracca.
The power surge in the Jedi Cruiser's medical bay, however, attracted the Scrapper Guild and the activity was reported to the Empire, bringing Crosshair and his new troopers to their door. The power Tech restored for the surgeries was turned against them as the Empire first used cannons then the engine bay to try to eliminate Clone Force 99.