Of course you can!
That's what Open Source Hardware is all about! And, if you need more information about how a particular module works, it's most likely in our GitHub repository.
Being an electronic adventurer doesn't come without a little risk! :) Please keep in mind–modules damaged through modification attempts are unable to be replaced.
Take your time and plan out your modifications carefully! We also probably won't be able to give you in-depth help with your electrical engineering, but feel free to ask by contacting us.