I cannot find any info on this unit using the given model number.
Please check it.

First I would check the power.
Try flipping the breaker off/on slowly, sometimes you can loose half the line without actually tripping the breaker.
If this does nothing, check the voltage at the plug
L1 to L2 should be 240 volts
L1 to Neutral and L2 to Neutral, both should be 120 volts.
If OK
Unplug the unit and check the wires at the terminal strip in the machine to make sure none are loose or burned out
If OK
Check the power at the terminal strip.
[COLOR="Red"]Be careful as 240 volts is lethal !!! [/COLOR]

Next I would check to see if it has a thermal fuse for power to the control board power supply.
This will be a torpedo shaped device in one of the wires close to the control board.
I cannot say if your unit uses this without a model number that I can look up.
If it has one check it with a meter, should be 0 ohms.

Here are your parts
Parts for Whirlpool RBD305PDQ2 Oven - AppliancePartsPros.com

See the attachment for the tech sheet.

There is a thermal fuse in this unit that kills power to the control board etc. (upper left corner of wiring diagram).

If the power is OK then check it.
With the power off to the unit it should be 0 ohms.
It is shown in section 06 towards the bottom of the list (oven thermal fuse).
It will be in one of the wires close to the control board.

If you click on a part's picture or description a new page will open with more info about it.

If it ios blown replace it then check that the oven temperature and oven fan work OK as they may have caused it to blow.