How do i replace 4 batteries mindlab DLS?

Hi I have an ole Mindlab DLS The 4 battery pack needs replacing but it looks to me like they are soldered in How do I get these replaced please??
I do not want to pull out wires and maybe break it It still works when plugged in but does not charge the batteries It is about 12 years old:confused:

They were not designed to be user-replaceable. You may want to get help from an electronics repair depot.