I too ran into the same problem. Waiting for an answer from someone who knows.
If you can get the system to boot and taking X-ray with the system powered on take out the sram. Replace the battery then put the sram back in the system. The system will write back to the sram.
If the system won’t boot (SRAM error) you’ll likely need to order a replacement unless you have all of the setup to write to a sram card.
You’d need a specific writer to convert to card.
I ended up calling a company Chesapeake Medical Systems and they sent replacement out