|MEGA File Sharing Service is not Free! Avoid it.|
Download Link: https://mega.nz/#!opgX1YRK!urL6_i1esm_nD-tiwyinzICgMGGkSU33HaxNclu246Q
Mirror: E5663_30.1.B.1.33_R7A_India Generic_1298-2221.ftf.torrent
We couldn't find the stock 5.1 firmware for Latin-America region, but we already tested the ftf of Android 5.0 (E5663_30.0.B.1.33_1297-3937_Customized-MY). When flashing to the phone some warnings appeared and the overall functions are totally fine, no issues except the built-in software updater is not working, the app downloaded update package from 5.0 to android 5.1 but when applying it, the android robot appears on the screen but immediately the Xperia M5 Dual restarts and failed to update the software.
Full directory: http://scrv.zapto.org/public/
So next step is as we saw in some forum, install the update using the full firware we are sharing here but not checking "wipe userdata" and see if personal data remains. Do not try this at home, at least not without making a backup. And if your battery is fine, we don't recommend updating the firmware when it is working in normal condition. Yeah, we know, 5.1 update comes with several bug fixes and makes the phone more battery efficient, but perhaps is not worth the risk or loosing files or even, hope never happens to you, brick it.