It is likely touchngo credit is not stored in your card.
Only the card serial/pin is stored in the card.
In this case, they just need to build a card reader in lrt booth/toll booth.

If the credit is stored in the card, then they need to build a card reader/writer in lrt booth/toll booth, why spend more while they can save?

If you tamper with the card, they can just make your card tidak sah in your next transaction, then you need to go to touch n go center and submit your card for investigation, then they will know what you did and you will not get a refund.

no matter how, it is a lose lose situation.

May be.

I bought an RM 300 credit card for RM 100 before long time ago, used it only 2 times before it was blocked for further transaction.
Went to TnG centre and check, they said the card is faulty, they can issue a refund if I can find out the owner. (not sure if they will really issue a refund or report police instead)