Koepel:
When a sketch stops inside the Wire.endTransmission(), there might be a shortcut of SDA to GND or from SCL to GND or a shortcut between SDA and SCL. In this case, you might also have blown the sensor.
The Master could not come out-of Wire.begin/Wire.end session due to (very probably) non-availability of the ACK signal/pulse from the Slave. The following diagram indicates that the SDA line quickly assumes LH level after the sampling of the ACK (present or not present) signal, and the SCK is already at LH level during the sampling of the ACK signal. If ACK is not received, SCL will be stretching as much as is needed until WDT/waiting boundary comes into action. Therefore, it is hard to justify the opinion that the SDA/SCL lines might get shorted together or with GND during this situation?
Koepel:
I think that you might have connected a 5V 40 mA digital output form the Arduino Mega 2560 board
Should it be 40 mA or 20 mA?