My Ultra 64gb card seems to have died.

the best solution is this

as sandisk does not disclose info on what is in their premium SD cards, it seems very unlikely that they contain tier 1 MLC nand. for the said application here, the endurance of MLC and a premium controller are of huge benefit. Both Transcend and Samsung disclose which cards are mlc and which are tlc…for this type of use, mlc ftw