I have this ( "California lilac" (genus Ceanothus)) in my garden and planted it as a very small plant this time last year ,in late September it had one bud on it! A the end of April start of may this year, I found masses of buds all over it and the plant itself has grown immensely in just one year! But at no time has it dropped leaves making it look dead. If its the same as my plant it probably is dead. But I suggest you leave it for at least a year just to see what happens! I had a shrub I had thought dead and did just this and to my suprise (& delight) it came to life the following year ). Bye and good luck with the plant.
james