LiPo chemistry is complex, there are many possible causes of battery puffing and failure.
Some causes include:
* Early in life: bad battery chemistry
* End of life: "expected" failure.
* Wrong charge voltage (most cells are only rated to 4.2V, but some phones expect 4.4V cells and will charge them to this)
* Mixture of high ambient temps and holding the voltage at max for long periods of time
* (Citation needed for this one, not certain if proven) micro-charge and discharge patterns.
pressing on the LCD touchscreen
Are you suffering bad or fake touch events? If so then that needs to be addressed separately.
new phone battery
New phone or new battery?
Either way does your country have decent warranty laws? Puffing battery in a phone is a major failure.