" guru lEkayeTuvaNTi guNiki teliyaka pOdu "
In the book Tyagaraja Saraswata Sarvaswam, this song is given slightly differently which obviates the difficulty of two negatives:
gurulEka eTuvamTi guNiki teliyagabOdu
The phrase teliyagabOdu can mean: teliyaga = to understand, bOdu = not possible, with only one negative.
In his book, "samgIta saurabhamu ", Dr S Pinakapani also gives the same pATham for this song.
The whole pallavi will now mean: Without a preceptor, ie without the guidance and compassion of an enlightened guru, one cannot learn the truth about Para Brahma. I submit that this blends well with the meaning of the rest of the song.