Agilent Keysight 3034a X-Series does not show traces

[Machlee]

Hi.
I was unlucky enough to break the oscilloscope when I tried to unsolder the battery. After this operation, when turned on, everything worked except for the presence of traces. Or sometimes they appear but very nosy. 

[TheSteve]

Ouch, was the board flexed a bunch when you were working on it?

[Machlee]

Surely, the battery terminals were difficult to remove, and my friend had to make an effort by prying the battery up with a screwdriver.

[JacobPilsen]

I think he is not your friend anymore.
Low temperature desoldering alloy (like InBiSn or BiInPbSn) should be your friend...

On the other hand, it is possible that the real fault is located at the opposite end of the board.
There may be a faulty U700, or a damaged DC/DC.

Have you tried to see if the signal that passed through the AFE (analog front-end) is undamaged?
There are lanes between the AFE and U700, and there are terminating resistors at the start and end where the signal can be observed with a second oscilloscope.