facebook/opt-350m · Pretraining error

I was pre-training the facebook opt 350m model on text file. While training after 15 steps the training loss is becoming zero. Can you help me with this.
Code I used
if script_args.load_in_kbits in [4, 8]:
    load_in_4bit = script_args.load_in_kbits == 4
    load_in_8bit = script_args.load_in_kbits == 8
    if script_args.modules_to_save is not None:
        load_in_8bit_skip_modules = script_args.modules_to_save.split(",")
    else:
        load_in_8bit_skip_modules = None
    quantization_config = BitsAndBytesConfig(
        load_in_4bit=script_args.load_in_kbits == 4,
        load_in_8bit=script_args.load_in_kbits == 8,
        llm_int8_threshold=6.0,
        load_in_8bit_skip_modules=load_in_8bit_skip_modules,
        bnb_4bit_compute_dtype=compute_dtype,
        bnb_4bit_use_double_quant=script_args.double_quant,
        bnb_4bit_quant_type=script_args.quant_type,  # {'fp4', 'nf4'}
    )
else:
    load_in_4bit = False
    load_in_8bit = False
    quantization_config = None
if quantization_config is not None:
    logger.info(f"quantization_config:{quantization_config.to_dict()}")

if script_args.model_name_or_path:
    torch_dtype = (
        script_args.torch_dtype
        if script_args.torch_dtype in ["auto", None]
        else getattr(torch, script_args.torch_dtype)
    )
    device_map = {"": int(os.environ.get("LOCAL_RANK") or 0)}
    model = AutoModelForCausalLM.from_pretrained(
        script_args.model_name_or_path,
        from_tf=bool(".ckpt" in script_args.model_name_or_path),
        config=config,
        # cache_dir=script_args.cache_dir,
        # revision=model_args.model_revision,
        use_auth_token=True if script_args.use_auth_token else None,
        torch_dtype=torch_dtype,
        low_cpu_mem_usage=True,
        device_map=device_map,
        load_in_4bit=load_in_4bit,
        load_in_8bit=load_in_8bit,
        quantization_config=quantization_config,
    )
    
else:
    model = AutoModelForCausalLM.from_config(config)
    n_params = sum({p.data_ptr(): p.numel() for p in model.parameters()}.values())
    logger.info(
        f"Training new model from scratch - Total size={n_params/2**20:.2f}M params"
    )

if script_args.load_in_kbits in [4, 8]:
    model = prepare_model_for_kbit_training(
        model, use_gradient_checkpointing=script_args.gradient_checkpointing
    )
model.config.use_cache = False
model_vocab_size = model.get_output_embeddings().weight.size(0)
tokenizer_vocab_size = len(tokenizer)
logger.info(f"Model vocab size: {model_vocab_size}")
logger.info(f"Tokenizer vocab size: {tokenizer_vocab_size}")
if model_vocab_size != tokenizer_vocab_size:
    logger.info(f"Resize model vocab size to {tokenizer_vocab_size}")
    model.resize_token_embeddings(len(tokenizer))

if script_args.peft_path is not None:
    logger.info("Peft from pre-trained model")
    model = PeftModel.from_pretrained(
        model, script_args.peft_path, device_map=device_map
    )
else:
    logger.info("Init new peft model")
    target_modules = script_args.trainable.split(",")
    modules_to_save = script_args.modules_to_save
    if modules_to_save is not None:
        modules_to_save = modules_to_save.split(",")
    lora_rank = script_args.lora_rank
    lora_dropout = script_args.lora_dropout
    lora_alpha = script_args.lora_alpha
    logger.info(f"target_modules: {target_modules}")
    logger.info(f"lora_rank: {lora_rank}")
    peft_config = LoraConfig(
        task_type=TaskType.CAUSAL_LM,
        target_modules=target_modules,
        inference_mode=False,
        r=lora_rank,
        lora_alpha=lora_alpha,
        lora_dropout=lora_dropout,
        modules_to_save=modules_to_save,
    )
    model = get_peft_model(model, peft_config)
for name, module in model.named_modules():
    if isinstance(module, LoraLayer):
      module = module.to(torch.float16)
        # if script_args.bf16:
        #     module = module.to(torch.bfloat16)
        # if script_args.fp16:
        #     module = module.to(torch.float16)
    if "norm" in name:
        module = module.to(torch.float16)
    if "lm_head" in name or "embed_tokens" in name:
        if hasattr(module, "weight"):
          module = module.to(torch.float16)
            # if script_args.bf16 and module.weight.dtype == torch.float32:
            #     module = module.to(torch.bfloat16)
            # if script_args.fp16 and module.weight.dtype == torch.float32:
            #     module = module.to(torch.float16)
model.print_trainable_parameters()
logger.info(f"model.modules_to_save: {model.modules_to_save}")
old_state_dict = model.state_dict
model.state_dict = (
    lambda self, *_, **__: get_peft_model_state_dict(self, old_state_dict())
).__get__(model, type(model))