Anet A8 - SkyNet3D freezes randomly at boot
The Anet A8 is a low end printer which works better after installing a better (read safer) than stock firmware (stock firmware does not have thermal runaway protection which is considered to be a hazard). It is good that you flashed another firmware that does have thermal runaway protection. 

The electronics of the Anet A8 are also questionable, the stock connectors are not rated for their task and wires could have been of better quality and thickness. 

Now that your older SkyNet3D firmware does not boot properly anymore, it would be time to check all the leads, possibly use new wires of proper gauge and flash a new version of a more recent firmware. SkyNet3D has been forked from Marlin Firmware and is no longer maintained as all functionality has been implemented for Anet printers in the Marlin sources.

If your printer still is giving you problems then when booting, a new set of electronics (e.g. board and steppers) would help out.