Cannot upgrade Galaxy Y GT-S5360 with new firmware using Kies Whenever I try to click "upgrade", my phone suddenly disconnects from Kies but the download prompt still runs. After the download process completes, Kies suddenly closes and there are no changes with my phone.
If the answer to my comment is No, then update Kies, and try again.

If the answer to my comment is yes, then try the following:


Place your phone manually into download mode, and attempt the update again.
Kill all Kies processes using the task manager, and then open the program again.
Ensure your USB cable and USB port are working properly (sometimes a weak connection can cause issues)
Erase all the data on your android (do a factory reset) and try again (I put this last, as you lose all your data, so should only be tried AFTER you have tried everything else you can think of).