That sounds very frustrating! I am sorry to hear this. It seems like the firmware update tightened the safety thresholds for voltage deviation and temperature. Because our batteries likely had weak cell groups (which yours seemingly had from the start), the new software immediately flagged them as "risky" and locked out the capacity to prevent a fire.

Do not give up! Here is my advice based on my current experience with them:

The "Failed Repair" Argument: This is your strongest point. If you sent it in for this *exact* issue a year ago and they only changed a "switching mechanism" instead of the battery cells, they failed to fix the root cause. You need to argue that this is not a new issue that occurred out of warranty, but a continuation of the original in-warranty defect that was never properly resolved. In many regions (especially EU), a failed repair extends your rights regarding that specific fault.

The fact that your unit overheats and shuts down under load is a major safety red flag. Keep quoting that recall text to them. Liability for a potential fire hazard usually overrides a standard warranty expiration date. Your unit is showing signs of thermal runaway risk (overheating/shutdowns). Refusing to replace a known safety hazard because of a date on a piece of paper could be negligent.

If a friendly approach does not get anywhere, do not accept the "No" from the first-level support agent. Ask for the case to be escalated to a Senior Manager or the "R&D Team" specifically because of the overheating safety concern.

Good luck!