Electronic – Bonding strain gauges to ABS

The power dissipated in strain gauge elements should always be far less than the power level at which you can do them any harm. Even connecting the "excitation voltage" across a single bridge element should do it no harm, eve though this would not be a useful thing to do. The implications are that you have done something which is fundamentally incorrect. The voltage used must be substantially greater than the rated voltage for the damaged part.

One possible reason for one only gauge being damaged is that the output is grounded or connected to v+ or to some other voltage so that theundamaged gauge "sees" little or no voltage.
What is your half-bridge midpoint connected to?

Do you have a data sheet
What is (or was) the gauge resistance for each part?
What is the applied voltage?
What power dissipation do you expect and what is the rated dissipation?

Resistor \$R_G\$, between pins 8 and 9 of the INA125, sets the gain of the instrumentation amplifier, which is given by:

$$ G=4+\dfrac{60,000}{R_G}. $$

If your output range is only one volt, and you want 5 V, reduce \$R_G\$ according to that equation, until G is 5 times higher.

If you want the details:

$$ k=\dfrac{G_{new}}{G_{old}} $$$$ R_{Gnew}=\dfrac{15000·R_{Gold}}{15000 k - R_{Gold} + k R_{Gold}} $$

The INA125's output is not rail to rail, so either use a supply > 5 V, to get a 5 V output range, or use a +5 V supply, and get an output range smaller than 5 V. Even if you adjust AREF of the Arduino to match your highest voltage, you will still lose range near the 0 V level.