HTC One M7 easy to battery cover removal - YouTube
The Black Store BN07100 Battery for HTC One M7 802D 802T 802W 801E 801N HTC One, Htl22, M7, One, One 801e, One 802d, One 802t, One LTE (2300mAh) with 3 Months Warranty :
Android Revolution | Mobile Device Technologies: How To: recalibrate battery life on HTC devices