Yes, you can upgrade your device to the compatible latest version via Samsung Odin. Technically, Samsung Galaxy Alpha can be upgradable to 5.0.2 (Lollipop). Although you cannot receive the Software updates, you can completely wipe the current firmware and flash 5.0.2 (Lollipop) firmware on your device using the Samsung Odin, which is the official stock firmware flashing tool for Samsung Galaxy smartphone. (1) First, download the Odin flashable firmware file for your device. (This XDA thread will help you) (2) Now, extract the firmware file and there you will be able to find out five MD5 files (3) Install USB drivers on your computer if you have not installed yet (4) Then, download Odin program on your PC (No official site and use download resource you trust and Odin3_v3.09 Recommended for Kikat ) (5) Extract the file and run the Odin program as "Admnistator" (6) Turn off your device (7) Press & Hold Power+Volume down + Home buttons at the same time until you get the "Download/Odin Mode" (8) Next, connect...
I would like to suggest a cheaper way than replacing a router? But you need jailbreak for this. You can install SignalRefresh Cydia Tweak on your device and boost the signal strength. The tweak is available in Bigboss repository in Cydia apps store. If you feel you need to try this but do not know about jailbreaking will www.cydiacloud.com be useful
Have you tried the battery booster app such as Greenify..These apps hibernate misbehaving apps and save battery power while saving CPU. Technically, they work on both on both rooted and non-rooted devices. But, works better when grants system-level access. As this is the Samsung device, you can try Odin to get root access. I hope this website and this guide ++https://odindownload.com/root-android++ would help you
It seems that you device has stuck in boot loop. The most common and popular method is hard resetting your device.But it seems that hard resetting has not worked for you.So, try flashing your device after downloading the correct firmware file for your device. Since you have bought the device from Thailand you need to check if the device is using and international firmware or country specific firmware.Here you can have complete guide ++samsungodin.com++