Format Failed C1-2755-9 -

If all else fails, it is highly likely that your SD2Vita adapter is simply dead. These items are cheaply produced, and "dead on arrival" units are frequent in the community. Purchasing a new, reputable adapter (sometimes referred to as V6) is often the only permanent fix.

If you use an SD2Vita adapter with a microSD card and see C1-2755-9 on the internal memory card: format failed c1-2755-9

Original PS Vita 1000 models have an internal clock battery that, when failing, can cause erratic I/O errors: If all else fails, it is highly likely