I recently had some plumbing done in my house I needed the hot water lines put under my concrete slab. The lumber simply cut the lines bent them down and reconnected the lines. He said this was ok because it was soft copper . I now am getting only warm water to my master bathroom instead of hot water like I did before the work was done . I feel like he may have connected the lines backwards when reconnecting any suggestions or thoughts

do you have normal hot water everywhere else?

How he reconnected them is important, but may have nothing to do with this problem.

Yes but warm not hot like it was before the work was done

There a few possibilities, but we would have to be there and do our own testing to see if we could determine the problem.

Is the floor warm now?

you can't answer 'yes' and then say it is not as hot.
if the whole house is 'not as hot' then there is either a problem with the water heater or a leak under the slab.