Open the case up including the side panels and investigate the latching method.
The front panel (FP) should have either push-posts that 'pop' into holes in the case front, or tabs that clip onto the case frame.
If the former, you may need to gently wedge a wide blade screwdriver between FP and case and twist to start the post to come loose if it is simply being stubbornly tight.
If the latter, you will have to remove the side panels to get access to the tabs that need to be flexed in or out to release the FP.