Unlimited career change starting from mechanic

This is the 40,000th year that the empire has ruled the galaxy. The glory of the Great Crusade has long been lost in the dust of history. Su Yu traveled through time and opened his eyes to see the ruined planet in front of him, with a confused look on his face.
On this planet, there are extremely dilapidated war machines that stretch for thousands of kilometers, alien behemoths whose roars can shatter mountains and rivers, and radiation that can cause further damage to the surrounding environment just by moving. Alien beast——
There is everything here except hope.
Regardless of whether he wanted to or not, Su Yu, who had struggled to survive for three years and was inevitably infected with radiation sickness in the end, seemed to be one of the desperate people.
Until his career panel, which allows for unlimited career changes, was finally opened.
"Ding!"
"It is detected that the host has met the prerequisites. Do you want to take up the occupation [Mechanic]?"
"After completing this profession, you can gain professional experience and improve your professional level from daily maintenance, recycling, and assembly of mechanical creations. With each upgrade, you can gain an increase in physical fitness..."
Looking at the old gun parts piled up in his repair room, Su Yu's eyes lit up like never before!
Many years later, at the core of the empire, at the highest point of the Terran world, the mechanic from the Ruined Star, the Ghost Shadow Blade of the Dead Wasteland, the restarter of the Titan Weapon Plan, the Governor of the Broken Star Territory, the Lord of Mechanical Ascension, the Supreme Throne of the Forge World, Su Yu looked at the torrent of steel coming from below and waved his hand to give the order!
[Our goal is to make the (second) (crossed out) empire great again! 】