The Optra Ecot-limited does not start when cold

It's a rough and problematic Optra; it won't start when cold, only after trying for several minutes. It only has 95,000 km, and all maintenance is up to date: spark plugs, coil, sensors, timing belt—everything has been scanned and there are fault codes. Yesterday it backfired and the timing belt, which was only a month old, broke. It's a tough situation; I'd appreciate any opinions.

If it's hard to start when cold, first check if there's spark at the cylinders. If there is, it's a fuel problem, either too much or too little. But to narrow down the problem, we need to know what's missing. A broken belt can happen at many points, from the condition of the belt to the condition of the tensioner bearing, etc.