They may still yet be recoverable but with a little loss. Had the vents popped, they would be going to recycle, plain & simple.
1st thing first and all of this is a PITA but if done right, it saves your keister.
1- Discharge the cells to at least 3.60V each.
2- Compress the cells in a "Clamp" BUT NOT HARD...a Light Hand Squeeze tight and continue to discharge the cells till they reach 3.2 volts each.
3- While discharging below 3.60V, recheck the "squeeze" frequently, you want to keep it SNuG but not under serious pressure. As the cells discharge the bloat will reduce slowly, DO NOT FORCE or apply too much pressure, it has to be gentle.
4- Once all cells are at 3.200V evenly, then you can "squeeze" the cells to Hand Tight and let them sit for a couple of days with nothing connected, not even busbars across the cells. Over time you will see voltage changes but also the bloating will "SLOWLY" reduce. Remember to keep checking that the pressure is constant and even.
- Use "blocks" on the ends to distribute the pressure evenly and to prevent any one spot from getting more pressure.
- When completing (after 4 days of rest under pressure) you can then check to make sure they flattened out (may not be perfect) check your voltages per cell.
- Bring each cell (alone) up to 3.450 and allow the charger to "saturate" the cells to the point where they do not take more than 2A. All the while under pressure (compression).
- Once all cells have reached 3.45 & saturated, then you can reconnect them in parallel and take them up to 3.500-3.600 (no higher) and again allow to saturate down to <2A taken.
- Now the crappy part... At this point the cells will still settle a bit so give them a minimum of 4 hours, (12 is the golden spot).
-- Recheck the settled voltage, IF they are all close +/-50mv DO A HAPPY DANCE ! If within 100mv still okay and happy... too much more, then cell is suspect but NOT out of the game, a quick topping again should level it up so do that and retest after 4-12 hours for that cell.
It is TEDIOUS and quite boring as it takes forever *will feel like it" but if it saves the cells, it's worth it.
Never leave charger unattended for long and always verify the charger output voltage against what is seen at the cell terminals.
Hope it helps, Good Luck.,