The answer from Payam Toloo, Owner of Payam Data Recovery:
It is unusual, but this situation occurs frequently.
A 50% success rate is quite favorable. Often, we encounter phones that power off at approximately 5% battery and subsequently fail to reactivate.
Based on our experience, this is typically attributable to liquid damage. The phones we examine have usually sustained some form of liquid exposure, such as saltwater or swimming pool water. The device may function for a period before powering off or failing to charge once the battery is depleted.
We have encountered instances where customers reported their phone worked for three days post-liquid exposure, leading them to believe no damage had occurred. Others reported that their phone abruptly ceased functioning two or three weeks later. This is usually due to a short circuit within the electronics.
We disassemble the phone, separate the circuit board, identify the fault, and repair the short circuit by restoring the electronics. The phone will then function temporarily, allowing for a complete backup to be created. However, continued use is not advised. We will provide an iTunes backup, along with all photos and videos. There is a strong probability we can assist you with this issue.
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