How do I update the OS on my device?
I have a an HTC Sensation with Android 2.3.4. I tried to check for updates. It says that there are no new updates. Is there any way to update my system to Android 4.0 manually?
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This page from HTC's website should help you. This might depend on your location and carrier. So please go through the site.
Another option, if you are ready to void your warranty, you can go for a custom ROM like CyanogenMod.