BTW, if your unit has a TDS3BATB, that battery has been recalled by Tektronix. They will replace it for free (normal cost is like $750-$1000!). I bought a very nice used TDS3024 a few months ago for cheap because the dead battery was giving a rather misleading warning on boot up. I pulled the battery and the warning went away. Then I looked into replacing (super expensive) or rebuilding the battery pack and found out about the recall.
Tek paperwork said to ship the old battery back to them, two day air, at their expense. That would be illegal, so I paid the local UPS store around $40 to pack and ship it to them properly.