i Agree with chucko. You can try recovering that lipo... Use the balance charger port and isolate the 2 batteries positve and negative poles. Charge the one with 2.51v back to 3.0v using the NiMH settings at low Ampere. Stop the charging if it get past 3.0v and rest it for about 5mins and see if it maintains the voltage.

If it does maintain it, then you are lucky, chancess are you didn't damage it.

Now isolate the other batery with the 5.08v, and use a 4 to 6v dc motor (a small FA-130 type would be good enough) or a 6.0v light bulb to drain it back to 3.0v.

Again rest the battery and see if it maintains the charge. If it does, cycle it twice (balance charge to full-rest-and then discharge) before using it.

HTH