Very important and situational question

You risk being blacklisted by immigration so wiould not be able to  enter Malaysia or work in Malaysia in the future.

The company should report that you abandoned the intended job. This will be noted in the online immmigration DB used at airports

The EP would need to be cancelled to be recruited by another company. If you try to enter the country you may well be stopped, as you would have been labelled an absonder.

Hopefully it's not a fake EP stamped in your passport and you have not entered on a tourist visa. There are other issues here such as avoiding the correct procedure of clearances and obtaining a VDR single entry visa.

The company may well want to retrieve costs from you (plus anything else mentioned in the contract of employment you signed) and therefore you could be listed as a debtor.

You may need to obtain a new passport.