I second bdb484's answer that your remaining option is to file a Petition in the U.S. Supreme court.
Beware of the Rules of the Supreme Court, as the specs are more intricate than those of a state supreme court.
I assume that your grounds for appeal are ultimately traceable to the equal protection of the laws (and due process, as you accurately replied to @ohwilleke). Therefore, in your Petition you'll need cite as "Constitutional Provision Involved" the XIV Amendment, Section 1, of the U.S. Constitution. Try to follow how others structure/present their petition, which is what I did in preparation for 17-1560 and 17-1576.
I'd also like to direct your attention to Lawrence v. State Tax Comm., 286 U.S. 276, 283 (1932), where the U.S. Supreme Court stated:
Even though the claimed constitutional protection be denied on non-federal grounds, it is the province of this Court to inquire whether the decision of the state court rests upon a fair or substantial basis.
Depending on the particulars of the issue with certificate of service, you may want to support your position using Brewer v. Office of Employee Appeals, 163 A.3d 799, 804 (2017), where the Washington D.C.'s top court stated:
The record shows an unbroken effort by a pro se petitioner, operating by mail from her San Francisco, California, address, to properly comply with somewhat arcane filing rules.
The point is not whether the rules in your jurisdiction are arcane as well, but that the Brewer court disapproved of the rather intransigent approach the appellee took towards the plaintiff/appellant.
A petitioner has 90 days to file his petition in the U.S. Supreme Court. Don't leave it to the last minute, as drafting it and preparing the prerequisite 40 copies in booklet format takes time. Go for it!