Is the red light still in a blinking state now that all printing has stopped ?
The blinking red light does cover a number of potential causes but most of them are Toner/cartridge related.
it can be a temporary error such as printer having a communication issue or similar but that would be cleared at power off.
The other causes are
1. low Toner
2. Empty Toner
3. The Toner cartridge reaching it's page count quota.
As the printer continued to print for a time with the error it would appear the cartridge was approaching the page quota or the toner was nearing empty and the a error light was a warning of this. Having now either run out of toner or reached the Cartridge life end the printer will now not print until the issue is solved.
It's not always the case that feint areas will appear on prints as the toner runs low. If the Toner is well distributed in the cartridge it can uniformly exhaust rather than in isolated areas as can happen if the Toner spread is uneven.
If it is due to the Cartridge count reaching it's trigger then there could be Toner still present even though the cartridge is no longer usable.
Yes i'm afraid so unless you can obtain a refill kit from a third party supplier.
That would consist of new Toner and a small circuit which attach's to the cartridge which records the toner level etc.
If a cartridge is in good condition they can be refilled a few times successfully but i have not had personal experience of doing it on your model so can't say how readily available the refill kits are for a 2510
a quick look pulled up this re refills.